Q.1 Which of the following is a primary immunodeficiency disorder?
HIV infection
DiGeorge syndrome
Malnutrition
Chemotherapy-induced neutropenia
Explanation - Primary immunodeficiency disorders are genetic or congenital defects in the immune system. DiGeorge syndrome is caused by a deletion in chromosome 22 leading to thymic hypoplasia.
Correct answer is: DiGeorge syndrome
Q.2 Severe Combined Immunodeficiency (SCID) is characterized by:
Defective B-cell function only
Defective T-cell function only
Defects in both T-cell and B-cell function
Overactive immune system
Explanation - SCID involves profound impairment of both humoral and cellular immunity, leading to severe infections early in life.
Correct answer is: Defects in both T-cell and B-cell function
Q.3 Which virus is most commonly associated with secondary immunodeficiency?
Influenza virus
Human Immunodeficiency Virus (HIV)
Epstein-Barr Virus
Hepatitis A virus
Explanation - HIV infection causes acquired immunodeficiency (AIDS) by progressively destroying CD4+ T-cells.
Correct answer is: Human Immunodeficiency Virus (HIV)
Q.4 Which immunoglobulin deficiency is the most common primary immunodeficiency?
IgA deficiency
IgG deficiency
IgM deficiency
IgE deficiency
Explanation - Selective IgA deficiency is the most common primary immunodeficiency, often asymptomatic but may predispose to mucosal infections.
Correct answer is: IgA deficiency
Q.5 The hallmark feature of Chronic Granulomatous Disease (CGD) is:
Defective neutrophil oxidative burst
Absent B-cells
Low IgG levels
Defective T-cell receptor
Explanation - CGD results from mutations in NADPH oxidase, preventing neutrophils from producing reactive oxygen species required to kill microbes.
Correct answer is: Defective neutrophil oxidative burst
Q.6 Which primary immunodeficiency is associated with ataxia and telangiectasia?
Wiskott-Aldrich syndrome
Ataxia-telangiectasia
DiGeorge syndrome
Hyper IgM syndrome
Explanation - Ataxia-telangiectasia is caused by mutations in the ATM gene, leading to neurological symptoms, telangiectasias, and immune defects.
Correct answer is: Ataxia-telangiectasia
Q.7 Hyper-IgM syndrome is due to a defect in:
Class switch recombination
Somatic hypermutation
CD19 signaling
Toll-like receptor function
Explanation - In Hyper-IgM syndrome, B-cells cannot switch from IgM to other isotypes due to CD40 ligand or AID enzyme defects.
Correct answer is: Class switch recombination
Q.8 Patients with Bruton's agammaglobulinemia lack which immune cells?
B-cells
T-cells
NK cells
Neutrophils
Explanation - Bruton’s agammaglobulinemia is caused by a mutation in the BTK gene, leading to absence of mature B-cells.
Correct answer is: B-cells
Q.9 Chediak-Higashi syndrome is associated with:
Defective phagolysosome fusion
Defective complement proteins
Defective IgG production
Defective T-cell receptor signaling
Explanation - Chediak-Higashi syndrome is a rare autosomal recessive disorder causing impaired lysosomal trafficking and defective phagolysosome fusion.
Correct answer is: Defective phagolysosome fusion
Q.10 Wiskott-Aldrich syndrome triad includes eczema, recurrent infections, and:
Neutropenia
Thrombocytopenia
Anemia
Hypogammaglobulinemia
Explanation - Wiskott-Aldrich syndrome is characterized by eczema, recurrent infections, and thrombocytopenia due to WAS gene mutation.
Correct answer is: Thrombocytopenia
Q.11 HIV primarily infects which type of immune cells?
CD4+ T-cells
CD8+ T-cells
B-cells
NK cells
Explanation - HIV infects CD4+ T-helper cells using gp120 binding to CD4 and chemokine receptors.
Correct answer is: CD4+ T-cells
Q.12 Which complement deficiency is associated with recurrent Neisseria infections?
C1 deficiency
C3 deficiency
C5-C9 deficiency
C2 deficiency
Explanation - Deficiency of terminal complement components (C5-C9) impairs the membrane attack complex, predisposing to Neisseria infections.
Correct answer is: C5-C9 deficiency
Q.13 A hallmark of DiGeorge syndrome is:
Hypocalcemia
Hyperkalemia
Hyponatremia
Hyperglycemia
Explanation - DiGeorge syndrome involves thymic aplasia and parathyroid hypoplasia, leading to hypocalcemia due to low parathyroid hormone.
Correct answer is: Hypocalcemia
Q.14 Which test is most commonly used to diagnose HIV infection?
Western blot
ELISA for HIV antibodies
PCR for influenza virus
VDRL test
Explanation - HIV screening is typically done with ELISA for anti-HIV antibodies, confirmed by Western blot or PCR.
Correct answer is: ELISA for HIV antibodies
Q.15 A newborn with SCID is most prone to infections by:
Opportunistic pathogens
Fungal infections only
Bacterial infections only
Viral infections only
Explanation - Due to combined T- and B-cell defects, SCID patients are highly susceptible to a broad range of opportunistic infections.
Correct answer is: Opportunistic pathogens
Q.16 Which of the following is an example of secondary immunodeficiency?
Bruton's agammaglobulinemia
SCID
HIV/AIDS
Wiskott-Aldrich syndrome
Explanation - HIV/AIDS is an acquired form of immunodeficiency caused by viral infection, unlike primary genetic disorders.
Correct answer is: HIV/AIDS
Q.17 Which lab finding is seen in X-linked agammaglobulinemia?
Absent B-cells and low immunoglobulins
Absent T-cells only
Low neutrophils only
Elevated IgE levels
Explanation - X-linked agammaglobulinemia presents with severely reduced B-cells and almost absent immunoglobulins in serum.
Correct answer is: Absent B-cells and low immunoglobulins
Q.18 Common Variable Immunodeficiency (CVID) primarily affects:
B-cell differentiation
T-cell receptor function
Neutrophil oxidative burst
Complement activation
Explanation - CVID results from impaired B-cell differentiation into plasma cells, leading to low immunoglobulin levels.
Correct answer is: B-cell differentiation
Q.19 Which is the gold standard treatment for SCID?
Bone marrow transplantation
Antibiotics
IV fluids
Chemotherapy
Explanation - Bone marrow (hematopoietic stem cell) transplantation is the most effective treatment for SCID.
Correct answer is: Bone marrow transplantation
Q.20 Nezelof syndrome is associated with:
Thymic hypoplasia
IgE deficiency
Neutropenia
Complement deficiency
Explanation - Nezelof syndrome is a rare congenital immunodeficiency caused by thymic hypoplasia and defective T-cell immunity.
Correct answer is: Thymic hypoplasia
Q.21 Which cytokine therapy is beneficial in Chronic Granulomatous Disease?
IL-2
IFN-γ
TNF-α
IL-4
Explanation - IFN-γ enhances macrophage and neutrophil microbicidal activity, useful in managing CGD.
Correct answer is: IFN-γ
Q.22 Patients with complement C3 deficiency are most prone to:
Bacterial infections
Viral infections
Fungal infections
Parasitic infections
Explanation - C3 deficiency impairs opsonization and complement activation, leading to recurrent bacterial infections.
Correct answer is: Bacterial infections
Q.23 The major defect in Job’s syndrome (Hyper-IgE syndrome) is:
Impaired neutrophil chemotaxis
Absent B-cells
Absent IgM
Low complement proteins
Explanation - Hyper-IgE syndrome is due to defective STAT3 signaling, leading to impaired neutrophil chemotaxis and high IgE.
Correct answer is: Impaired neutrophil chemotaxis
Q.24 Which laboratory test helps confirm Chronic Granulomatous Disease?
Nitroblue tetrazolium (NBT) test
Coombs test
Western blot
ELISA
Explanation - The NBT test assesses neutrophil oxidative burst function, which is defective in CGD.
Correct answer is: Nitroblue tetrazolium (NBT) test
Q.25 Which immunodeficiency is characterized by recurrent bacterial infections and absence of tonsils?
X-linked agammaglobulinemia
CVID
SCID
DiGeorge syndrome
Explanation - In Bruton's agammaglobulinemia, B-cells fail to mature, causing absence of tonsils and lymphoid tissue.
Correct answer is: X-linked agammaglobulinemia