Question 1

For which one among the following diseases no vaccine is yet available?

Accepted Answer

Answer reason: Tetanus, measles, and mumps all have long-established vaccines (tetanus toxoid and the MMR vaccine). Malaria historically lacked an effective, widely available vaccine; only recently have first-generation vaccines been recommended with modest efficacy. In the conventional context of this question, malaria is the disease without a routinely available, highly effective vaccine. Therefore, malaria is the best answer among the given choices.

Question 2

BCG is used against?

Accepted Answer

Answer reason: BCG (Bacille Calmette–Guérin) is a live attenuated vaccine derived from Mycobacterium bovis and is used to prevent tuberculosis, especially severe forms like miliary TB and TB meningitis in children. It does not protect against typhoid, cholera, or diphtheria, which have their own specific vaccines (Vi/Ty21a for typhoid, oral cholera vaccines, and diphtheria toxoid respectively). Therefore, the correct option is tuberculosis.

Question 3

Immune mechanism of Liver lies in?

Accepted Answer

Answer reason: Kupffer cells are the liver’s resident macrophages lining the hepatic sinusoids. They provide innate immune defense by phagocytosing bacteria, endotoxin, and debris from portal blood and by producing cytokines. While sinusoids and acini are anatomical structures, the primary immune function is executed by Kupffer cells.

Question 4

Which blood component is responsible for fighting disease?

Accepted Answer

Answer reason: White blood cells (leukocytes) are the primary cells of the immune system that identify and destroy pathogens through processes such as phagocytosis and antibody-mediated responses. Red blood cells mainly transport oxygen, platelets mediate clotting, and plasma is the liquid portion carrying proteins and solutes. Therefore, WBCs are responsible for fighting disease.

Question 5

Immunoglobulin provides?

Accepted Answer

Answer reason: Immunoglobulins are antibodies given exogenously that provide immediate humoral protection by neutralizing pathogens, which is passive immunity. The recipient does not mount their own immune response, so protection is temporary. Active immunity requires antigen exposure and endogenous antibody production, and cell-mediated immunity is T-cell driven rather than antibody-based.

Question 6

The White blood cell (leucocytes) contains ____ that fight/ defend the body or system of Man...?

Accepted Answer

Answer reason: Phagocytes (such as neutrophils and monocyte/macrophages) are white blood cells specialized in engulfing and destroying pathogens and cellular debris, providing frontline innate immune defense. Lymphocytes also participate in immunity but are a separate subtype focusing on adaptive responses and antibody production. Plateletcytes/thrombocytes are platelets involved in hemostasis, not direct pathogen defense. Therefore, the WBCs that fight by ingestion and destruction of microbes are phagocytes.

Question 7

IPV is use during immunization to prevent?

Accepted Answer

Answer reason: IPV stands for inactivated poliovirus vaccine. It contains killed poliovirus and induces protective humoral immunity against poliomyelitis, preventing paralytic disease. It is given by injection as part of routine childhood immunization schedules.

Question 8

Tetanus is controlled by?

Accepted Answer

Answer reason: Tetanus is prevented by active immunization with tetanus toxoid–containing vaccines (TTCV), such as TT or Td formulations. These induce neutralizing antibodies against tetanospasmin, the toxin of Clostridium tetani. BCG protects against tuberculosis and OPV against poliomyelitis. While DPT includes a tetanus component, TTCV is the specific vaccine category used to control tetanus.

Question 9

In blood transfusion reactions, which antibody mainly causes agglutination?

Accepted Answer

Answer reason: Acute hemolytic transfusion reactions from ABO incompatibility are mediated by naturally occurring anti-A or anti-B antibodies, which are predominantly IgM. IgM is pentameric, making it highly effective at agglutinating red blood cells and activating complement, leading to intravascular hemolysis. IgG is more characteristic of Rh alloimmunization (e.g., hemolytic disease of the newborn), IgA is mucosal, and IgE mediates allergic reactions.

Question 10

IgG is an example of?

Accepted Answer

Answer reason: IgG stands for immunoglobulin G, which is a class of antibodies. It is produced by plasma cells and is the most abundant immunoglobulin in serum, providing long-term humoral immunity. IgG mediates functions such as neutralization, opsonization, complement activation, and can cross the placenta. Therefore, it is an antibody, not an antigen, hormone, or enzyme.

Question 11

Which white blood cells form antibodies?

Accepted Answer

Answer reason: lymphocytes differentiate into plasma cells that synthesize and secrete antibodies (immunoglobulins), a key function of the adaptive immune response. Neutrophils primarily perform phagocytosis, basophils release histamine and mediate allergic responses, and monocytes become macrophages/dendritic cells for phagocytosis and antigen presentation. Therefore, only B cells are responsible for antibody formation.

Question 12

HIV mainly attacks?

Accepted Answer

Answer reason: HIV binds the CD4 receptor and co-receptors (CCR5/CXCR4) on CD4+ helper T lymphocytes, enters the cells, and progressively depletes them, leading to immunodeficiency. Erythrocytes lack CD4 and are not infected. Platelets are anucleate cell fragments and not primary targets. Neutrophils are part of innate immunity and are not the main cells HIV infects.

Question 13

Vaccine used for Smallpox?

Accepted Answer

Answer reason: The smallpox vaccine uses live vaccinia virus, a related orthopoxvirus that induces cross-protective immunity against variola (smallpox). MMR protects against measles, mumps, and rubella; BCG is for tuberculosis; and OPV is for poliomyelitis. Therefore, vaccinia is the correct agent used in smallpox vaccination.

Question 14

Vaccination is part of?

Accepted Answer

Answer reason: Vaccination is a method of immunization that introduces antigens (or genetic instructions for antigens) to stimulate the immune system to develop protective immunity. This leads to immune memory via activation of B and T lymphocytes and production of antibodies, reducing risk of future infection or severe disease. Digestion, circulation, and respiration are body functions but are not the primary biological process targeted by vaccines.

Question 15

Which complement is an opsin as well and helps in phagocytosis?

Accepted Answer

Answer reason: C3b is the major complement opsonin that covalently binds to microbial surfaces and promotes phagocytosis by binding complement receptors (e.g., CR1) on neutrophils and macrophages. This opsonization enhances recognition and ingestion of pathogens. C4b can participate in classical/lectin pathway convertase formation and may opsonize to a lesser extent, but C3b is the principal opsonin. IL-1 is a cytokine, not a complement component or opsonin.

Question 16

Immunity provided by DPT is?

Accepted Answer

Answer reason: DPT is a vaccine containing toxoids/antigens that stimulate the recipient’s own immune system to produce antibodies and immunologic memory. Because this protection results from the body actively responding, it is classified as active immunity. Since it is induced by vaccination rather than by natural infection, it is artificial active immunity. Passive immunity would involve receiving preformed antibodies (e.g., immunoglobulin), which is not the case with DPT.

Question 17

Lymphoma is a disease of?

Accepted Answer

Answer reason: Lymphoma is a malignancy of lymphocytes, which are key cells of the immune system found in lymph nodes and other lymphoid tissues. It commonly presents with painless lymphadenopathy and may include systemic “B symptoms” (fever, night sweats, weight loss). Because the primary pathology is in lymphoid/immune tissues rather than organs like the liver or heart, the best answer is immune system.

Question 18

Which cells are primarily targeted by HIV in the human body?

Accepted Answer

Answer reason: HIV primarily infects cells that express the CD4 receptor, most notably CD4+ T helper lymphocytes. Viral entry is mediated by binding to CD4 along with co-receptors (CCR5 or CXCR4), leading to progressive depletion of these cells. Loss of CD4+ T-cell function impairs both cell-mediated and humoral immune responses, resulting in opportunistic infections characteristic of AIDS. Red blood cells and platelets lack CD4 receptors, and B cells are not the primary direct target.

Question 19

Which immunoglobulin is the first antibody produced in a primary immune response?

Accepted Answer

Answer reason: In a primary immune response, naïve B cells initially secrete IgM because it is the first isotype produced before class switching occurs. IgM forms pentamers, making it effective at agglutination and complement activation early in infection. After T-cell–dependent class switching and affinity maturation, IgG becomes the predominant antibody in later primary and especially secondary responses.

Question 20

T-cell mature in body?

Accepted Answer

Answer reason: T lymphocytes originate from bone marrow progenitors but undergo maturation and selection in the thymus, where they develop functional T-cell receptors and self-tolerance (positive and negative selection). The spleen is a secondary lymphoid organ involved in immune responses, not primary maturation. The liver and kidney are not sites of T-cell maturation in normal physiology.

Question 21

Which immunoglobulin is abundant in breast milk?

Accepted Answer

Answer reason: Secretory IgA is the predominant immunoglobulin in breast milk (especially colostrum). It provides passive mucosal immunity by coating the infant’s gastrointestinal and respiratory mucosa and preventing pathogen adherence, with minimal inflammatory response. IgG is the major serum antibody and is mainly transferred transplacentally, while IgM is an early response antibody and IgE is associated with allergy and parasitic defense.

Question 22

ELISA test is used to detect?

Accepted Answer

Answer reason: ELISA (enzyme-linked immunosorbent assay) is an immunoassay used to detect and/or quantify antigen–antibody reactions, most commonly measuring specific antibodies in a patient sample (e.g., HIV screening tests). The assay uses enzyme-labeled reagents that produce a color change when the target antibody (or antigen) is present. Blood pressure, blood sugar, and hemoglobin are measured using different physiologic measurements or laboratory chemistry/hematology methods, not ELISA.

Question 23

Colostrum is especially rich in?

Accepted Answer

Answer reason: Colostrum (early breast milk) is characteristically high in immunologic components, especially secretory IgA, along with other immune cells and antimicrobial factors. These immunoglobulins provide passive mucosal protection to the newborn’s gastrointestinal and respiratory tracts during the first days of life. Compared with mature milk, colostrum is lower in fat and lactose but concentrated in protective proteins rather than iron, glucose, or water.

Question 24

Which type of immunity is given by tetanus toxoid?

Accepted Answer

Answer reason: Tetanus toxoid is an inactivated toxin (toxoid) vaccine that stimulates the recipient’s immune system to produce their own antibodies and memory cells against tetanus. This is artificially acquired active immunity because protection develops via an immune response after vaccination. Passive immunity would involve giving preformed antibodies (e.g., tetanus immune globulin) rather than inducing antibody production. Natural and maternal immunity refer to immunity acquired through infection or transplacental/breast milk antibody transfer, respectively.

Question 25

HLA DR4 is Associated with Which of following?

Accepted Answer

Answer reason: HLA-DR4 (an MHC class II allele) is classically associated with increased susceptibility to rheumatoid arthritis, especially seropositive RA. This reflects genetic predisposition affecting antigen presentation and downstream autoimmune T-cell activation. By contrast, psoriasis is more associated with HLA-Cw6, celiac disease with HLA-DQ2/DQ8, and SLE with other HLA-DR variants (e.g., DR2/DR3).

Question 26

Which of the following tests is used to detect AIDS?

Accepted Answer

Answer reason: ELISA (enzyme-linked immunosorbent assay) is a screening test used to detect antibodies to HIV (and/or HIV antigen in 4th-generation assays), which identifies HIV infection associated with AIDS. Widal test is for typhoid fever serology, Mantoux is for tuberculosis screening, and a lipid profile measures cholesterol/triglycerides and is unrelated to HIV diagnosis. Positive ELISA screening results are typically confirmed with supplemental/confirmatory testing per guidelines.

Question 27

BCG vaccination confers on an individual?

Accepted Answer

Answer reason: BCG is a live attenuated vaccine (derived from Mycobacterium bovis) that stimulates the recipient’s own immune system to develop protection, which is active immunity. Passive immunity refers to receiving preformed antibodies (e.g., immunoglobulin), not vaccination. Vaccines do not “cure” existing tuberculosis; they are preventive. Immunity from vaccines is not immediate, as it requires time for an adaptive immune response to develop.

Question 28

What is the function of CD4+ T cells?

Accepted Answer

Answer reason: CD4+ T cells are helper T lymphocytes that orchestrate immune responses by releasing cytokines and activating other immune cells. They promote B-cell antibody production, enhance macrophage activation, and help activate CD8+ cytotoxic T cells. In contrast, antibody production is a B-cell/plasma cell function, and direct killing of infected cells is primarily mediated by CD8+ T cells.

Question 29

Which cell are called Soldiers of the body?

Accepted Answer

Answer reason: White blood cells (leukocytes) are called the “soldiers of the body” because they provide immune defense by recognizing, attacking, and eliminating pathogens and abnormal cells. Different leukocyte types (e.g., neutrophils, lymphocytes, monocytes) carry out innate and adaptive immune responses such as phagocytosis and antibody/cell-mediated immunity. Red blood cells primarily transport oxygen, and platelets primarily support hemostasis, so they are not the main defensive cells.

Question 30

Most important point in endotoxins mediated shock is that it?

Accepted Answer

Answer reason: Endotoxin (LPS) from gram-negative bacteria activates macrophages via TLR4, triggering release of key proinflammatory cytokines, notably TNF-α and IL-1, which drive fever, vasodilation, capillary leak, and hypotension characteristic of septic (endotoxin-mediated) shock. Among the listed options, IL-1 is the best match to this central inflammatory mediator concept. IL-3 is more associated with hematopoiesis, IL-4 with Th2/allergic responses, and IL-7 with lymphocyte development, making them less directly tied to endotoxin shock pathogenesis.

Question 31

Which antibody crosses the placenta?

Accepted Answer

Answer reason: IgG is the only major immunoglobulin class that is actively transported across the placenta via the neonatal Fc receptor (FcRn). This transfer provides the fetus/newborn with passive humoral immunity during late pregnancy and early infancy. IgM is too large (pentameric) to cross the placenta, and IgA primarily protects mucosal surfaces (not placental transfer). IgE is mainly involved in allergic responses and does not cross the placenta in clinically meaningful amounts.

Question 32

An immunological reaction is also known as?

Accepted Answer

Answer reason: In transfusion/infusion contexts, an “immunological reaction” commonly refers to an allergic, IgE-mediated hypersensitivity response, which is anaphylaxis in its severe form. Anaphylaxis presents with rapid onset airway, breathing, and circulatory compromise due to mast-cell mediator release. Shock is a physiologic state that can result from anaphylaxis but is not synonymous with “immunological reaction.” Acute haemolytic reaction is immune-mediated too, but it is specifically due to hemolysis from ABO incompatibility rather than the general term typically used for allergic immunologic reactions.

Question 33

Immunity is mostly related to...?

Accepted Answer

Answer reason: Immunity is primarily mediated by lymphocytes: B cells produce antibodies (humoral immunity) and T cells coordinate and execute cell-mediated immune responses. These cells are central to antigen recognition, immunologic memory, and adaptive immune specificity. Monocytes contribute to innate defense via phagocytosis and antigen presentation, but they are not the main cells defining adaptive immunity. Red blood cells carry oxygen, and thrombocytes (platelets) are mainly involved in hemostasis, not immune function.

Question 34

A patient having AIDS may also have one of the following disease?

Accepted Answer

Answer reason: AIDS causes profound immunosuppression (especially low CD4+ T cells), increasing the risk of malignancies. Cervical carcinoma is an AIDS-defining cancer strongly associated with persistent HPV infection in immunocompromised patients. HIV/AIDS is also linked with increased risk of certain hematologic malignancies (classically non-Hodgkin lymphoma), and the question’s broad intent is that multiple cancers may coexist in AIDS; thus the best keyed option among those provided is “All of the above.”.

Question 35

The breast milk component that helps protect against infection is?

Accepted Answer

Answer reason: Breast milk contains immune factors, most notably secretory IgA antibodies, which provide passive immunity by coating the infant’s mucosal surfaces and helping prevent pathogen attachment and invasion. This reduces the risk of gastrointestinal and respiratory infections in the newborn. While fat and lactose provide calories and iron supports hematologic needs, they are not the primary anti-infective component.

Question 36

Which type of immunity is provided by tetanus immunoglobulin (TIG)?

Accepted Answer

Answer reason: Tetanus immunoglobulin (TIG) contains preformed antibodies against tetanus toxin, providing immediate protection without requiring the patient to mount an immune response. This is passive immunity because antibodies are transferred directly to the recipient. It is temporary and does not create immunologic memory, unlike active immunity induced by tetanus toxoid vaccination.

Question 37

The type of immunity acquired through sub-clinical infection in which immunity is?

Accepted Answer

Answer reason: A sub-clinical infection means the person is exposed to a pathogen and mounts their own immune response, even without obvious symptoms. This produces endogenous antibodies and immune memory, which defines active immunity. Because the exposure occurs naturally via infection (not vaccination or antibody administration), it is natural active acquired immunity. Passive immunity would involve receiving preformed antibodies and does not create long-term immune memory.

Question 38

Which immune cells are primarily destroyed by HIV?

Accepted Answer

Answer reason: HIV primarily infects and progressively depletes CD4+ T-helper lymphocytes by binding to the CD4 receptor (and co-receptors such as CCR5/CXCR4) and replicating within these cells. Loss of CD4+ cells impairs both cell-mediated immunity and effective activation of B cells and macrophages, leading to opportunistic infections and AIDS. Red blood cells and platelets are not the primary target cells for HIV, and B-cell dysfunction occurs largely secondary to CD4+ depletion rather than direct primary destruction.

Question 39

Immuno globulin across the placenta is-?

Accepted Answer

Answer reason: IgG is the only major immunoglobulin class that crosses the placenta via Fc receptor–mediated transport (FcRn), providing passive immunity to the fetus/newborn. IgM is a large pentamer and does not cross the placenta; detection of fetal/neonatal IgM suggests in utero infection. IgA is primarily secretory (e.g., breast milk/mucosal protection) and IgE mediates allergic responses rather than placental transfer. Therefore, IgG is the correct choice.

Question 40

In infant presence of immuno globulins acts by-?

Accepted Answer

Answer reason: Infants receive immunoglobulins primarily through maternal transfer (IgG via placenta and IgA via breast milk), which provides immediate protection without the infant producing antibodies. Because these antibodies are provided from an external source, this is classified as passive immunity. Active immunity would require the infant’s own immune system to generate antibodies after infection or vaccination. Innate/natural immunity refers to non-specific defenses rather than transferred immunoglobulins.

Question 41

A patient is admitted to the hospital with signs and symptoms of systemic lupus erythematosus (SLE). Which test would support the diagnosis?

Accepted Answer

Answer reason: A positive antinuclear antibody (ANA) test is highly sensitive for SLE and is commonly used as an initial serologic test to support the diagnosis. CBC and ESR may be abnormal in SLE but are nonspecific and can be elevated/abnormal in many inflammatory or hematologic conditions. A hepatobiliary scan is unrelated to confirming SLE. Therefore, ANA is the best answer among the options provided.

Question 42

The grouping of blood is based on substances called?

Accepted Answer

Answer reason: ABO blood groups are determined by specific antigens (A and/or B) present on the surface of red blood cells. These RBC surface antigens define whether a person is type A, B, AB, or O. Plasma antibodies form against the ABO antigens that are not present on the individual’s own RBCs, but the grouping itself is based on the antigens.

Question 43

Which organ plays a major role in immunity?

Accepted Answer

Answer reason: The spleen is a key secondary lymphoid organ that filters blood and mounts immune responses to blood-borne pathogens. Its white pulp contains lymphocytes that recognize antigens and generate antibody and cell-mediated responses. It also helps remove opsonized bacteria and old or damaged red blood cells, supporting both immune surveillance and clearance.

Question 44

Rh factor is a type of?

Accepted Answer

Answer reason: The Rh factor refers primarily to the D antigen present on the surface of red blood cells. Individuals who express this antigen are Rh-positive, while those who lack it are Rh-negative. This antigen can trigger an immune response if Rh-negative individuals are exposed to Rh-positive blood (e.g., transfusion or pregnancy), which is why it is clinically important.

Question 45

Colostrum is rich in?

Accepted Answer

Answer reason: Colostrum (early breast milk) is particularly rich in immunologic factors, especially secretory IgA, which provides passive mucosal protection to the newborn. It also contains leukocytes and other antimicrobial proteins (e.g., lactoferrin), but immunoglobulins are the hallmark nutrient emphasized. Compared with mature milk, colostrum is relatively lower in fat and lactose (carbohydrate). Therefore, the best answer is immunoglobulins.

Question 46

Vaccine is activated by?

Accepted Answer

Answer reason: Vaccines work by introducing antigenic components (weakened/killed organisms or purified parts such as proteins or polysaccharides) that are recognized by the immune system. These antigens stimulate antigen-presenting cells and activate T and B lymphocytes, leading to antibody production and immune memory. Antibodies are produced as a result of vaccination rather than being what "activates" it. Platelets and hormones are not responsible for initiating vaccine-induced immune responses.

Question 47

Antibodies are produced by?

Accepted Answer

Answer reason: Antibodies (immunoglobulins) are produced by plasma cells, which are differentiated B lymphocytes—a type of white blood cell (WBC). RBCs primarily transport oxygen and do not participate in antibody production. Platelets function mainly in hemostasis and clotting. Plasma is the liquid portion of blood that carries antibodies but does not produce them.

Question 48

Vaccine is an example of?

Accepted Answer

Answer reason: Vaccines contain antigens (e.g., weakened/inactivated pathogens, pathogen components, or genetic instructions) that stimulate the immune system to mount a response. This exposure leads to activation of B and T cells and development of immunologic memory without causing the full disease in typical circumstances. Antibodies are produced by the body after exposure, antibiotics treat bacterial infections, and hormones are endocrine signaling molecules.

Question 49

HIV affects which system of the human body?

Accepted Answer

Answer reason: HIV primarily targets the immune system by infecting and destroying CD4+ T lymphocytes, leading to progressive immunodeficiency. As CD4 counts decline, the body becomes increasingly unable to mount effective immune responses, resulting in opportunistic infections and certain cancers characteristic of AIDS. While HIV can have neurologic and cardiovascular effects, the primary system affected is the immune system.

Question 50

Which in vitro test measures IgE levels against a specific allergen?

Accepted Answer

Answer reason: FAST (fluorescent allergosorbent test) is an in vitro assay designed to detect allergen-specific IgE by binding patient IgE to immobilized allergen and then using labeled anti-IgE for detection. In contrast, RIST measures total serum IgE rather than IgE directed against a particular allergen. Histamine release assays assess basophil activation/mediator release, not IgE quantification against a defined allergen. Therefore, FAST best matches “IgE levels against a specific allergen.”.

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