Immunology and Serology MCQs with Answer and Explanations | Chapter 7

Answer: IgM

IgM is the first immunoglobulin produced by the fetus in response to an infection. It is also the first antibody to be produced during the primary immune response because it is highly effective at forming antigen-antibody complexes due to its pentameric structure, which allows for multiple binding sites.

The other options are incorrect:

• IgG: Primarily received from the mother through the placenta, not directly produced by the fetus in response to infection.
• IgA: Primarily produced in mucosal surfaces like the gut, not the initial response in the bloodstream.
• IgD: Function not fully understood, but not the primary antibody in fetal immune response.

Answer: T-lymphocytes

Graft versus host reaction (GVHR) is primarily caused by T-lymphocytes. When donor T-cells recognize the recipient’s tissues as foreign, they initiate an immune response against the host’s cells, leading to GVHR. This reaction is common in bone marrow and stem cell transplants where donor immune cells attack the recipient’s body.

The other options are incorrect:

• B-Lymphocytes: Produce antibodies, important in the immune response, but not the primary cause of GVHD.
• Monocytes: Develop into macrophages that engulf and destroy pathogens, not directly involved in recognizing and attacking host cells in GVHD.
• Leukocytes: A broad term for all white blood cells, including lymphocytes (T and B cells), monocytes, and others. GVHD specifically involves the T-lymphocyte subset.

Answer: IgM

IgM is the first immunoglobulin to be released after primary immunization. It is the initial antibody produced by B cells in response to an antigen and is crucial for the early stages of the immune response due to its ability to form pentamers, providing multiple binding sites for antigens.

The other options are incorrect:

• IgD: Function of IgD is not fully understood, but it’s not the primary antibody produced during a first encounter with an antigen.
• IgE: Primarily involved in allergic reactions, not the initial response in a primary immune response.
• IgG: Develops later after the initial immune response and is the most abundant antibody class, providing long-term immunity. It can also be passed from mother to fetus for protection.

Answer: Orally administered

BCG (Bacillus Calmette-Guérin) vaccine is not orally administered; it is typically given via intradermal injection. It is a live attenuated vaccine used primarily to protect against tuberculosis (TB).

The other options are incorrect:

• Live vaccine: BCG is indeed a live vaccine, containing a weakened form of the Mycobacterium bovis bacteria.
• T.B vaccine: This is accurate; BCG is the primary vaccine for tuberculosis.

Answer: Arthus reaction

The Arthus reaction is a type of hypersensitivity reaction that occurs when immune complexes (antigen-antibody complexes) deposit in tissues, leading to inflammation and tissue damage. This reaction is a type III hypersensitivity and histamine does not play a major role in it. Instead, it involves complement activation and neutrophil infiltration.

The other options are incorrect:

• Urticaria (hives): This is a type I hypersensitivity reaction mediated by IgE and histamine release from mast cells, causing rapid onset of wheals and itching.
• Asthma: This is also a type I hypersensitivity reaction involving IgE, histamine release, and airway inflammation leading to wheezing, shortness of breath, and chest tightness.
• Anaphylaxis: This is the most severe type I hypersensitivity reaction, involving widespread histamine release and potentially life-threatening symptoms.

Answer: CH2 domain

The binding site for the complement on the IgG molecule is located in the CH2 domain of the constant region of the heavy chain. This domain is responsible for interacting with the first component of the complement system (C1q) to initiate the classical pathway of complement activation.

The other options are incorrect:

• VL domain: The VL domain (variable light chain) is part of the Fab fragment responsible for antigen binding, not complement interaction.
• CL domain: The CL domain (constant light chain) also contributes to the Fab fragment structure and antigen binding.
• CH1 domain: The CH1 domain is located closer to the hinge region of the IgG molecule and doesn’t contain the primary binding site for C1q.

Answer: Systemic arthus reaction

Serum sickness syndrome is an example of a systemic Arthus reaction, which is a type III hypersensitivity reaction. It occurs when immune complexes (antigen-antibody complexes) form and deposit in various tissues, leading to inflammation and tissue damage. This typically happens after exposure to foreign proteins, such as antiserum or certain drugs.

The other options are incorrect:

• Anaphylactic: This is a severe type I hypersensitivity reaction mediated by IgE and massive histamine release, causing rapid and potentially life-threatening symptoms.
• Angioneurotic edema: This can be a component of both anaphylaxis and serum sickness, but it’s not the defining characteristic of serum sickness itself.
• Cell-mediated immunity: This type of immunity involves T-lymphocytes directly targeting and destroying infected or abnormal cells. Serum sickness is an antibody-mediated response (humoral immunity).

Answer: Plasma cells

Immunoglobulins, or antibodies, are secreted by plasma cells. Plasma cells are differentiated B cells that produce and release large amounts of antibodies, which play a critical role in the immune response by identifying and neutralizing pathogens such as bacteria and viruses.

The other options are incorrect:

• Macrophages: These are phagocytic cells that engulf and destroy pathogens and debris. They can present antigens to T-cells but don’t secrete antibodies.
• T-cells: These are lymphocytes responsible for cell-mediated immunity, directly targeting and killing infected or abnormal cells. They don’t produce antibodies.
• Neutrophils: These are phagocytic white blood cells involved in the early stages of the inflammatory response. They don’t produce antibodies.

Answer: Placental transfer of antibodies

Naturally acquired passive immunity occurs when a person receives antibodies from another person naturally. The placental transfer of antibodies from mother to fetus is a prime example of this type of immunity. During pregnancy, maternal IgG antibodies cross the placenta, providing the fetus with passive immunity against pathogens.

The other options are incorrect:

• Hepatitis vaccination: This is an example of artificially acquired active immunity. Vaccines stimulate the body’s immune system to develop its own antibodies against a specific pathogen.
• Gamma globulin injection: This is also an example of artificially acquired passive immunity. Gamma globulin is a blood product containing antibodies collected from many donors and can provide temporary protection against specific diseases.
• Immune blood transfusion: Similar to gamma globulin injection, this is another form of artificially acquired passive immunity. Transfusing blood from an immune individual can provide temporary protection against specific pathogens.

Answer: Endoplasmic reticulum

The synthesis of antibodies in plasma cells occurs in the endoplasmic reticulum (ER). The ER is responsible for the synthesis and folding of proteins, including immunoglobulins, before they are transported to the Golgi apparatus for further processing and secretion.

The other options are incorrect:

• Golgi body: The Golgi apparatus packages and modifies proteins synthesized in the ER, but it’s not the primary site of antibody synthesis.
• Nucleus: The nucleus houses DNA and is responsible for gene expression. It provides the instructions (mRNA) for antibody production, but the actual synthesis occurs in the ER.
• Mitochondria: Mitochondria are the cellular powerhouses responsible for energy production (ATP). They are not involved in protein synthesis.

Answer: IgE

IgE (Immunoglobulin E) is the immunoglobulin implicated in atopy (genetic predisposition to developing allergic reactions) and anaphylaxis (severe allergic reaction). It binds to mast cells and basophils, triggering the release of histamine and other mediators involved in allergic responses.

The other options are incorrect:

• IgM: While the first antibody produced in response to an infection, IgM is not a major player in allergies or anaphylaxis.
• IgG: The most abundant antibody class, IgG plays a role in long-term immunity but not typically involved in immediate hypersensitivity reactions like atopy and anaphylaxis.
• IgA: Primarily found in mucosal surfaces and secretions, IgA contributes to immunity at these sites but not a key player in atopy or anaphylaxis.

Answer: Spleen and the lymph nodes

The majority of antibodies are produced in the spleen and the lymph nodes. These organs are key sites where B lymphocytes mature and differentiate into plasma cells, which are responsible for producing antibodies as part of the adaptive immune response.

The other options are incorrect:

• Heart and the liver: These organs have important functions but are not involved in large-scale antibody production.
• Brain and the meninges: The brain is responsible for control and coordination, and the meninges protect the brain and spinal cord. Neither is involved in antibody production.
• Thymus and the appendix: The thymus plays a crucial role in T-lymphocyte maturation, and the appendix has some immune function, but neither is a major site of antibody production.

Answer: Delayed reaction

Anaphylaxis is characterized by an immediate and severe allergic reaction to an allergen, leading to symptoms such as hives, swelling, difficulty breathing, and in severe cases, anaphylactic shock. Delayed reactions are not typically associated with anaphylaxis; instead, they occur over a longer period of time following exposure to an allergen.

The other options are incorrect:

• Immediate reaction: This is a hallmark feature of anaphylaxis. Symptoms like wheezing, swelling, and trouble breathing appear rapidly.
• Passive transfer by serum: In theory, if serum from someone with a severe allergy to a specific antigen were injected into another person, it could potentially cause an allergic reaction in the recipient due to the presence of IgE antibodies. However, this is not a common way anaphylaxis occurs.

Answer: IgA

IgA is the most abundant immunoglobulin found in exocrine secretions like saliva, tears, mucus, and breast milk. It plays a crucial role in protecting mucosal surfaces from pathogens by neutralizing them and preventing their attachment to epithelial cells.

The other options are incorrect:

• IgG: While IgG is the most common antibody in the blood, it’s not the primary immunoglobulin in exocrine secretions.
• IgD: IgD is found in low quantities and plays a role in B cell activation, but it’s not a major component of exocrine secretions.
• IgM: IgM is primarily found in the blood and plays a role in the early immune response, but it’s not as prevalent in exocrine secretions as IgA.

Answer: Vasoactive mediators

Mast cell degranulation, triggered by antigen-antibody interaction, releases various chemicals stored in the granules. These chemicals, collectively known as vasoactive mediators, are responsible for the symptoms of anaphylaxis.

The other options are incorrect:

• Lysosomes: Lysosomes contain digestive enzymes but are not responsible for anaphylaxis.
• Proteolytic enzymes: While proteolytic enzymes are present in mast cell granules, they are not the primary mediators of anaphylaxis.
• Lymphotoxins: Lymphotoxins are cytokines produced by activated T cells and natural killer cells, not stored in mast cell granules, and are not directly involved in anaphylaxis
• .

Answer: Serum sickness

Serum sickness is an immune complex hypersensitivity reaction characterized by the formation of antigen-antibody complexes in the bloodstream, leading to symptoms such as fever, rash, joint pain, and lymphadenopathy.

The other options are incorrect:

• Atopic allergy: Atopic allergies are type I hypersensitivity reactions involving IgE antibodies and mast cell degranulation. They cause symptoms like hay fever, asthma, and eczema.
• Transfusion reaction: Transfusion reactions can involve various mechanisms, including type I, II, or IV hypersensitivity reactions, depending on the specific incompatibility between donor and recipient blood.
• Contact dermatitis: Contact dermatitis is a type IV hypersensitivity reaction involving T-lymphocytes and skin inflammation. It occurs upon direct contact with an allergen rather than immune complex deposition.

Answer:C5a

C5a is a potent chemotactic factor generated during complement activation. It attracts immune cells, particularly neutrophils, towards the site of infection or inflammation. This directed movement helps initiate a targeted immune response.

The other options are incorrect:

• C2a: C2a is an intermediate component in the classical and lectin pathways of complement activation. While it plays a role in the cascade, it doesn’t directly attract immune cells.
• C3b: C3b is another crucial component of the complement system. It serves as an opsonin, tagging pathogens for phagocytosis by immune cells, but it doesn’t have direct chemotactic activity.
• C4a: C4a is a minor chemotactic factor compared to C5a. Its primary function is to contribute to inflammatory responses.

Answer: IgA

IgA, specifically secretory IgA (SIgA), is the most abundant immunoglobulin found in saliva. SIgA is specifically designed to protect mucosal surfaces like the mouth and throat from pathogens. It neutralizes toxins and prevents bacteria and viruses from attaching to epithelial cells.

The other options are incorrect:

• IgD: IgD is present in very low quantities and plays a role in B cell activation. It’s not a major component of bodily fluids like saliva.
• IgE: IgE is primarily associated with allergic reactions and is found in much lower concentrations in saliva compared to IgA.
• IgG: IgG is the most common antibody in the blood, but its presence in saliva is limited. It’s not specifically adapted for mucosal defense like IgA.

Answer: All of the above

A false-positive VDRL (Venereal Disease Research Laboratory) test can occur due to various reasons besides syphilis. Here’s a brief explanation of why each option can contribute to a false positive:

• Yaws: Yaws is a bacterial infection caused by Treponema pallidum subspecies pertenue, closely related to the syphilis bacteria. This similarity can lead to a cross-reaction in the VDRL test, causing a false positive.
• Lepromatous Leprosy: This severe form of leprosy involves Mycobacterium leprae infection, which can sometimes trigger a false-positive VDRL due to mechanisms not fully understood.
• Malaria: Malaria, a parasitic infection, can cause non-specific immune system activation, leading to a false-positive VDRL in some cases.

Answer: Both VDRL test &TPHA test

The diagnostic investigation for syphilis typically involves a combination of serological tests, including the VDRL (Venereal Disease Research Laboratory) test for screening and the TPHA (Treponema pallidum hemagglutination assay) test for confirmation.

The other options are incorrect:

• TPI test: TPI (Treponema pallidum immobilization) test is an older test method for diagnosing syphilis but is less commonly used compared to newer serological tests like VDRL and TPHA.
• VDRL test: While the VDRL test is used for screening syphilis, it alone may not provide a definitive diagnosis and requires confirmation with additional tests like the TPHA test.
• TPHA test: The TPHA test is used to confirm the diagnosis of syphilis but is not typically used as a standalone test for screening. It is used in conjunction with other tests like the VDRL test for diagnosis.

Answer: Syphilis

The Wassermann test, although a historical milestone, is no longer the preferred diagnostic tool for syphilis. Developed in the early 20th century, it’s a non-treponemal test that relies on detecting antibodies against non-specific components present in various infections. This can lead to false positives for conditions other than syphilis.

The other options are incorrect:

• Gonorrhea: Gonorrhea is a bacterial infection caused by Neisseria gonorrhoeae. The Wassermann test wouldn’t detect antibodies specific to this bacteria.
• TB (Tuberculosis): Tuberculosis is caused by Mycobacterium tuberculosis and has its own diagnostic tests. The Wassermann test wouldn’t be effective for TB diagnosis.
• Typhoid: Typhoid fever, caused by Salmonella typhi bacteria, has specific diagnostic methods that don’t involve the Wassermann test.

Answer: 10

A complete initial series of tetanus vaccination with 3 doses of tetanus toxoid typically confers immunity for around 10 years. After this period, the level of immunity starts to decline, and booster shots are recommended to maintain protection against tetanus.

The other options are incorrect:

• 5 years: Immunity from the tetanus toxoid vaccine wanes over time. While some protection might linger beyond 10 years, it’s not guaranteed.
• 15 years: While some studies suggest immunity might last longer in some individuals, 10 years is the generally accepted timeframe for a booster shot.
• 20 years: The immune response tends to weaken after 10 years, and booster shots are crucial to maintain protection for longer durations.

Answer: Prognosis

The lepromin test is not the primary diagnostic tool for leprosy. While it can provide some information about past exposure to Mycobacterium leprae, the bacteria that causes leprosy, its usefulness lies mainly in prognosis.

The other options are incorrect:

• Diagnosis: Other tests like skin smears, biopsies, and antibody tests are more reliable for diagnosing current leprosy infection.
• Treatment plan: The lepromin test result doesn’t directly influence the specific leprosy treatment plan. Treatment decisions are based on the type and severity of the infection.
• Epidemiology: The lepromin test is not routinely used for epidemiological studies due to its limitations in accurately reflecting the prevalence of leprosy in a population.

Answer: O antibodies last longer and hence is not indicative of recent infection

In the Widal test, O antibodies are indicative of a past infection or vaccination rather than recent infection because they can persist in the bloodstream for a longer duration

The other options are incorrect:

• Base lines differ depending on the endemicity of the disease: This statement is true. Baseline titers in the Widal test can vary depending on the prevalence of the disease in a particular region.
• H antigen cannot differentiate between subtypes: This statement is true. The H antigen used in the Widal test is common among different serotypes of Salmonella typhi and cannot differentiate between them.
• High titre value in a single Widal test is not confirmative: This statement is true. A single high titre value in the Widal test is not confirmative of typhoid fever and requires further clinical correlation and possibly additional tests for confirmation.

Answer: Rheumatie fever

The ASO (Antistreptolysin O) test is used for the diagnosis of rheumatic fever, a systemic inflammatory disease that can develop as a complication of untreated or inadequately treated streptococcal infections, particularly streptococcal pharyngitis (strep throat).

The other options are incorrect:

• Rheumatoid arthritis: Rheumatoid arthritis is an autoimmune disease that doesn’t directly involve strep infection. Different diagnostic tests are used for rheumatoid arthritis.
• Typhoid fever: Typhoid fever is caused by Salmonella typhi bacteria, and the ASO test wouldn’t be helpful in diagnosing it.
• Rickettsial fever: Rickettsial fevers are caused by Rickettsia bacteria transmitted by ticks, mites, or lice. The ASO test wouldn’t be relevant for diagnosis.

Answer: Cardiac valves

The Group A carbohydrate of Streptococcus pyogenes cross-reacts with human cardiac valves, leading to the development of rheumatic heart disease, particularly affecting the heart valves.

The other options are incorrect:

• Synovial fluid: Streptococcus pyogenes does not typically cross-react with synovial fluid.
• Myocardium: While rheumatic fever can lead to myocarditis, the Group A carbohydrate of Streptococcus pyogenes primarily cross-reacts with cardiac valves rather than the myocardium.
• Vascular intima: Streptococcus pyogenes does not typically cross-react with vascular intima. The primary target of cross-reactivity is the cardiac valves, leading to rheumatic heart disease.

Answer: Cardiolipin

The reagin test, such as the Venereal Disease Research Laboratory (VDRL) test and the Rapid Plasma Reagin (RPR) test, uses cardiolipin as a key antigen. Cardiolipin is a phospholipid (a type of fat molecule with a phosphate group) found in the outer membranes of various cells, including those of bacteria.

The other options are incorrect:

• Plasminogen: Plasminogen is a blood protein that becomes converted into plasmin, an enzyme involved in blood clot breakdown. It’s not used in the reagin test.
• Palmityl lecithin: Palmityl lecithin is another phospholipid, but it’s not the specific phospholipid employed in the reagin test.
• Serine: Serine is an amino acid, not a phospholipid, and doesn’t play a role in the reagin test.

Answer: CD 4*

In tuberculosis (TB), cell-mediated immunity is primarily mediated by CD4-positive T cells, also known as helper T cells. These cells play a crucial role in activating macrophages to kill intracellular Mycobacterium tuberculosis bacteria.

The other options are incorrect:

• CD8+: CD8+ T lymphocytes are also important immune cells, but they primarily target and destroy virus-infected cells or cancerous cells. While they can play a role in TB immunity, CD4+ T cells are the central players in T.B cell-mediated immunity.
• B-lymphocytes: B-lymphocytes are responsible for antibody production (humoral immunity). While they can contribute to some aspects of TB immunity, cell-mediated immunity mediated by CD4+ T cells is the primary defense mechanism.
• None of the above: All immune responses involve lymphocytes, and CD4+ T cells play a well-defined role in cell-mediated immunity against TB.

Answer: All of the above

All the listed statements are true about the VDRL (Venereal Disease Research Laboratory) test:

• Non-Specific: The VDRL test is a non-treponemal test. It detects antibodies produced by the body in response to syphilis infection, but these antibodies can also be produced due to other infections or conditions.
• Slide Flocculation Test: The VDRL test is a slide agglutination test. It involves mixing serum with a cardiolipin antigen suspension on a slide. If antibodies against cardiolipin are present, they will clump together (flocculate) with the antigen, indicating a positive test.
• Best Followed for Drug Therapy: While a positive VDRL test suggests a syphilis infection, it doesn’t confirm it. More specific tests are needed for confirmation. However, a VDRL test can be used to monitor the effectiveness of treatment.

Answer: Typhoid

The Widal test is specific for typhoid fever. It is a serological test used to detect antibodies against specific antigens of Salmonella typhi, the bacterium that causes typhoid fever.

The other options are incorrect:

• Plague: Plague is caused by Yersinia pestis bacteria, and the Widal test wouldn’t be specific for detecting antibodies against it.
• Leprosy: Leprosy is caused by Mycobacterium leprae bacteria, and a different diagnostic approach is used.
• Pemphगोयid (Pemphrigoid): Pemphrigoid is an autoimmune blistering skin disease, and the Widal test wouldn’t be relevant for diagnosis.

Answer: Cell mediated immunity

The tuberculin skin test (TST) is a cell-mediated immunity test. It assesses the body’s immune response to previous exposure to Mycobacterium tuberculosis, the bacteria that causes tuberculosis (TB).

The other options are incorrect:

• Hemoral immunity: This test is not designed to assess antibody-mediated immunity (humoral immunity).
• Complement function: The tuberculin test doesn’t directly evaluate the complement system’s function.
• Phagocyte dysfunction: This test is not specific for identifying issues with phagocyte function (phagocytes are white blood cells that engulf and destroy pathogens).

Answer: Widal test

The Widal test is an agglutination test used in the diagnosis of typhoid fever. It detects antibodies against specific antigens of Salmonella typhi, the bacterium that causes typhoid fever, by observing agglutination reactions in serum samples.

The other options are incorrect:

• Eleks test: The Eleks test is an agglutination test used to diagnose brucellosis, a bacterial infection caused by Brucella species.
• Mantoux test: The Mantoux test is a tuberculin skin test, not an agglutination test. It assesses cell-mediated immunity to Mycobacterium tuberculosis, the bacteria that causes TB.
• Wasserman test: The Wasserman test, although historical, was a non-treponemal test used for syphilis diagnosis. It’s no longer the preferred method due to limitations in specificity.

Answer: FTAB

The FTA-ABS (Fluorescent Treponemal Antibody Absorption Test) is a specific treponemal test used to diagnose syphilis. It directly detects antibodies against Treponema pallidum, the bacteria that causes syphilis. This makes it highly specific for syphilis diagnosis compared to non-treponemal tests.

The other options are incorrect:

• Widal test: The Widal test is an agglutination test used to diagnose typhoid fever, not syphilis. It detects antibodies against Salmonella typhi bacteria.
• Wasserman test: The Wasserman test, although historical, was a non-treponemal test used for syphilis diagnosis. It’s no longer preferred due to limitations in specificity.
• Kahn test: Similar to the Wasserman test, the Kahn test was another non-treponemal test used for syphilis diagnosis. It also has limitations in specificity and is not routinely used anymore.

Answer: TPHA

The TPHA (Treponemal Hemagglutination Assay) is a specific test used to diagnose syphilis. It directly detects antibodies against Treponema pallidum, the bacteria that causes syphilis. This makes it highly specific for syphilis diagnosis compared to non-treponemal tests like VDRL and Kahn test.

The other options are incorrect:

• VDRL (Venereal Disease Research Laboratory): This is a non-treponemal test that detects antibodies produced by the body in response to syphilis infection, but these antibodies can also be caused by other infections or conditions.
• Kahn’s test: Similar to VDRL, the Kahn test is a non-treponemal test with limitations in specificity for syphilis diagnosis.
• Widal test: The Widal test is an agglutination test specific for typhoid fever, not syphilis. It detects antibodies against Salmonella typhi bacteria.

Answer: Hypoxanthine aminopterin thyminine

Hydridoma cells grow selectively in Hypoxanthine aminopterin thyminine (HAT) medium due to its ability to support the growth of hybrid cells (hydridomas) while inhibiting the growth of unfused myeloma cells and spleen cells.

The other options are incorrect:

• Polyethylene glycol: Polyethylene glycol is used in cell fusion techniques to facilitate the fusion of myeloma cells and B cells to form hybridomas but is not a selective growth medium.
• Hypoxanthine-guanine phosphoribosyl transferase (HGPRT): HGPRT is an enzyme involved in purine salvage pathway and is not directly related to selective growth of hydridoma cells.
• Both second and third: While both hypoxanthine-aminopterin-thymidine (HAT) and hypoxanthine-guanine phosphoribosyl transferase (HGPRT) are involved in selective growth of hydridoma cells, only HAT medium is commonly used for this purpose.

Answer: Plasma cells and myeloma cells

Hybridomas are formed by the fusion of plasma cells, which produce specific antibodies, with myeloma cells, which are immortalized cancer cells. This fusion creates hybrid cells capable of producing large quantities of a specific monoclonal antibody.

The other options are incorrect:

• Plasma cells and plasmids: Plasma cells do not naturally fuse with plasmids. Plasmids are small, circular DNA molecules commonly found in bacteria and are not involved in the formation of hybridomas.
• Myeloma cells and plasmids: Myeloma cells do not naturally fuse with plasmids. Plasmids are commonly used in genetic engineering techniques but are not involved in the formation of hybridomas.
• Plasma cells and bacterial cells: Plasma cells are mammalian immune cells, and bacterial cells are prokaryotic cells. They do not naturally fuse with each other, and bacterial cells are not involved in the formation of hybridomas.

Answer: HBV

Hepatitis B virus (HBV) is commonly referred to as serum hepatitis. This term originated from the early days when the exact cause of hepatitis was unknown, and the virus was transmitted through blood or serum-derived products.

The other options are incorrect:

• HCV (Hepatitis C Virus): Hepatitis C can also be spread through blood-borne contact, but it’s not typically referred to as serum hepatitis.
• HAV (Hepatitis A Virus): Hepatitis A is primarily transmitted through the fecal-oral route and not considered serum hepatitis.
• HIV (Human Immunodeficiency Virus): HIV targets the immune system and doesn’t cause hepatitis.

Answer: Non-immunogenic

Haptens are molecules that are non-immunogenic on their own but can become immunogenic when they bind to carrier molecules, such as proteins. This binding forms a complex that is recognized by the immune system, leading to an immune response.

The other options are incorrect:

• Immunogenic: Haptens themselves are not immunogenic because they are too small to elicit an immune response. However, when they bind to carrier molecules, they can induce an immune response.
• Antigenic: While haptens can become part of antigens when bound to carrier molecules, they are not inherently antigenic on their own.

Answer: IgM

IgM is the first antibody class produced by the immune system in response to an infection. It is generated rapidly and serves as an early defense mechanism against pathogens.

The other options are incorrect:

• IgG: IgG antibodies are produced later in the immune response and provide long-term immunity against pathogens.
• IgD: IgD antibodies are primarily found on the surface of B cells and have a role in the activation of B cells, but they are not typically the first antibodies formed after infection.
• IgE: IgE antibodies are involved in allergic reactions and defense against parasitic infections, but they are not typically the first antibodies formed after infection.

Answer: B-lymphocytes

Antibodies in our body are primarily produced by B-lymphocytes, a type of white blood cell. B-lymphocytes are responsible for the humoral immune response, producing antibodies to neutralize pathogens such as bacteria and viruses.

The other options are incorrect:

• T-lymphocytes (T cells): T cells are another type of white blood cell crucial for the immune response. However, their primary function is cell-mediated immunity, not antibody production.
• Monocytes: Monocytes are phagocytic white blood cells that engulf and destroy pathogens. They are not directly involved in antibody production.
• RBCs (Red Blood Cells): Red blood cells are responsible for oxygen transport in the body and don’t have a role in the immune response.

Answer: Hybridoma technology

Monoclonal antibodies are produced using hybridoma technology, which involves fusing a specific antibody-producing B cell with a myeloma cell to create a hybrid cell line capable of producing large quantities of a single type of antibody.

The other options are incorrect:

• Biotechnology: While monoclonal antibodies are indeed a product of biotechnology, specifically hybridoma technology, “biotechnology” alone is too broad a term to accurately describe the specific method of monoclonal antibody production.
• Fermentation Technology: Fermentation technology is a method used to produce various substances, including some proteins and pharmaceuticals, but it is not specifically used for monoclonal antibody production.
• None of these: The correct answer is that monoclonal antibodies are produced using hybridoma technology. Therefore, “None of these” is not the correct option.

Answer: Unbroken skin

The first line of defense in the body is the physical and chemical barriers, including unbroken skin, mucous membranes, and secretions like tears and saliva. These barriers prevent pathogens from entering the body and causing infections.

The other options are incorrect:

• Antibody molecules: Antibody molecules are part of the adaptive immune response and are produced in response to specific pathogens. They are not the first line of defense.
• Antigen molecules: Antigen molecules are foreign substances that trigger an immune response but are not themselves a component of the body’s defense mechanisms.
• Phagocytic cells: Phagocytic cells, such as macrophages and neutrophils, are part of the innate immune system and play a crucial role in engulfing and destroying pathogens. However, they are not the first line of defense; physical and chemical barriers are the initial defense mechanisms.

Answer: Affinity

The strength of the bond between an antigen and antibody is referred to as affinity. It describes the tightness of binding between a single antigen-binding site on an antibody and an epitope on an antigen.

The other options are incorrect:

• Avidity: Avidity refers to the overall strength of binding between multiple antigen-binding sites on a multivalent antibody and multiple epitopes on an antigen. It is determined by both affinity and the number of binding sites but is not synonymous with the strength of the bond between a single antigen and antibody.
• Covalent: Covalent bonds involve the sharing of electrons between atoms and are typically stronger than non-covalent bonds like those between antigens and antibodies. However, most antigen-antibody interactions are non-covalent in nature.
• None of these: The correct term for the strength of the bond between antigen and antibody is affinity. Therefore, “None of these” is not the correct option.
• a

Answer: Western blot

Western blot is a technique used to analyze protein antigens. It involves separating proteins based on their size through gel electrophoresis, transferring them to a membrane, and then detecting specific proteins using antibodies that bind to them.

The other options are incorrect:

• Southern blot: Southern blot is a technique used to analyze DNA fragments. It involves transferring DNA fragments from a gel to a membrane, followed by hybridization with a labeled DNA probe to detect specific sequences.
• Northern blot: Northern blot is a technique used to analyze RNA molecules. It involves separating RNA molecules based on size through gel electrophoresis, transferring them to a membrane, and then detecting specific RNA molecules using labeled probes.

Answer: IgG

IgG antibodies are the most abundant type of antibody found in the blood and can effectively cross the placenta from mother to fetus during pregnancy. This transfer provides the newborn with temporary passive immunity against pathogens the mother has encountered.

The other options are incorrect:

• IgA: IgA antibodies are found in mucus and secretions and are not efficiently transferred across the placenta.
• IgE: IgE antibodies are involved in allergic reactions and not in providing passive immunity.
• IgM: IgM antibodies are large and do not readily cross the placenta. They are primarily produced during the initial immune response and are not well suited for providing long-term passive immunity.

Answer: Conglutination

Conglutination is a specific type of agglutination reaction that relies on the complement system. In this test, complement proteins coat antigen-antibody complexes, causing them to clump together more readily, leading to visible agglutination.

The other options are incorrect:

• Haem agglutination: This refers to agglutination of red blood cells (RBCs) by antibodies, which can occur with or without complement involvement.
• Complement fixation: This is a different immunological technique that detects antigen-antibody complexes by their ability to “fix” complement proteins. Complement is not used to enhance agglutination in this case.
• Schultz Dale Phenomenon: This refers to the smooth muscle contraction caused by antigen-antibody interactions on mast cells, leading to allergic reactions. It’s not an agglutination reaction.

Answer: T cell

T cells are the primary players in the cellular immune response. They directly target and eliminate infected cells or cancer cells, as well as activate other immune cells through cytokine signaling.

The other options are incorrect:

• B cells: B cells are the key components of the humoral immune response, responsible for producing antibodies that circulate in the blood and neutralize pathogens.
• BT cells: There is no specific cell type called a BT cell in the immune system.
• Endothelial cells: These cells form the lining of blood vessels and lymphatic vessels. While they play a role in immune function, they are not directly involved in the cellular immune response.

Answer: IgG

IgG antibodies are the most abundant type of immunoglobulin found in human serum, constituting approximately 75-80% of the total immunoglobulins. They offer long-term protection against pathogens due to their stability and ability to activate various immune effector mechanisms.

The other options are incorrect:

• IgA: IgA is another important immunoglobulin, but it’s primarily found in mucosal secretions like saliva and tears, protecting these surfaces from pathogens. It’s present in much lower concentrations in the serum compared to IgG.
• IgE: IgE antibodies are involved in allergic reactions and are present in very small quantities in the blood. They are not a major component of the serum.pen_spark

Answer: 8%

Globulin is one of the major proteins found in human serum, typically accounting for around 8% of its total protein content. Globulins play a crucial role in the immune system, transporting substances throughout the body, and clotting blood.

The other options are incorrect:

• 12%: While globulin is important, 12% is slightly higher than the usual concentration found in serum.
• 16%: 16% is significantly higher than the typical range for globulin in human serum.
• 4%: 4% is considerably lower than the expected amount of globulin found in serum.

Answer: HEPV

HEPV, or Human Diploid Cell Vaccine, is a non-neural vaccine for rabies. It is produced using cultured human cells, eliminating the potential risks associated with nerve tissue used in older vaccines.

The other options are incorrect:

• Card vaccine: Also known as the Pasteur’s cord vaccine, this is a type of neural vaccine that utilizes rabbit spinal cord tissue.
• BPL (Beta-propiolactone vaccine): This is another type of neural vaccine made from inactivated rabies virus in nervous system tissue, treated with a chemical called beta-propiolactone.
• Simple (Semple vaccine): This is yet another historical neural vaccine prepared from inactivated rabies virus in dog brain tissue.