Fundamental aspects of immunology MCQs With Answer

Fundamental aspects of immunology MCQs With Answer

This collection of multiple-choice questions is designed specifically for M.Pharm students studying Immunotechnology. The set focuses on core immunology concepts—innate and adaptive immunity, antigen recognition, antigen presentation, immunoglobulin structure and function, complement, cytokines, hypersensitivity, and cellular mechanisms such as clonal selection, somatic hypermutation, and memory formation. Each question emphasizes mechanistic understanding and clinical relevance to help you apply principles in formulation, vaccine design, immunoassays, and therapeutic antibody development. Use these MCQs for self-assessment, revision before exams, and to strengthen problem-solving skills required in advanced pharmaceutical immunology.

Q1. Which of the following components are considered part of innate immunity?

• Physical and chemical barriers such as skin and mucosa
• Complement proteins and phagocytic cells like neutrophils and macrophages
• Pattern recognition receptors (e.g., Toll-like receptors)
• All of the above

Correct Answer: All of the above

Q2. Which region of an antibody determines antigen specificity and binds the epitope?

• Constant (C) region of the heavy chain
• Hinge region
• Variable (V) region of heavy and light chains
• Fc region

Correct Answer: Variable (V) region of heavy and light chains

Q3. MHC class II molecules typically present peptides derived from which source?

• Endogenous cytosolic proteins degraded by the proteasome
• Extracellular proteins internalized and processed in endosomal/lysosomal pathway
• Lipid antigens bound to CD1 molecules
• Non-peptidic small molecule haptens only

Correct Answer: Extracellular proteins internalized and processed in endosomal/lysosomal pathway

Q4. Which enzyme is essential for class switch recombination and somatic hypermutation in activated B cells?

• Terminal deoxynucleotidyl transferase (TdT)
• Activation-induced cytidine deaminase (AID)
• DNA polymerase delta
• RAG1/RAG2 recombinase

Correct Answer: Activation-induced cytidine deaminase (AID)

Q5. Activation of the complement cascade by antigen-antibody complexes primarily initiates which pathway?

• Lectin pathway via mannose-binding lectin
• Alternative pathway via spontaneous C3 hydrolysis
• Classical pathway (C1q binding to IgM or IgG)
• Coagulation pathway cross-talk

Correct Answer: Classical pathway (C1q binding to IgM or IgG)

Q6. Toll-like receptors (TLRs) and other pattern recognition receptors primarily recognize:

• Self-antigens to maintain tolerance
• Pathogen-associated molecular patterns (PAMPs)
• Peptides presented by MHC molecules
• Only viral nucleic acids and not bacterial components

Correct Answer: Pathogen-associated molecular patterns (PAMPs)

Q7. Natural killer (NK) cells rapidly kill target cells by recognizing:

• Upregulation of MHC class I molecules on stressed cells
• Antigen presented on MHC class II
• Loss or downregulation of MHC class I on target cells (missing-self recognition)
• Only antibody-coated cells through Fc receptors

Correct Answer: Loss or downregulation of MHC class I on target cells (missing-self recognition)

Q8. Compared to a primary immune response, a secondary (memory) humoral response is characterized by:

• Slower onset and lower antibody titers
• Predominantly IgM with low affinity
• Faster kinetics, higher magnitude, and higher-affinity IgG due to memory B cells
• Absence of class-switched antibodies

Correct Answer: Faster kinetics, higher magnitude, and higher-affinity IgG due to memory B cells

Q9. The primary biological role of Fc receptors on phagocytes is to:

• Bind antigen-binding fragments (Fab) and neutralize pathogens
• Bind the Fc portion of antibodies to mediate opsonization, phagocytosis and ADCC
• Present peptide antigens to T cells
• Induce somatic hypermutation in B cells

Correct Answer: Bind the Fc portion of antibodies to mediate opsonization, phagocytosis and ADCC

Q10. Which cytokine is a key driver of Th1 differentiation and promotes cell-mediated immunity?

• Interleukin-4 (IL-4)
• Interleukin-10 (IL-10)
• Interleukin-12 (IL-12)
• Transforming growth factor-beta (TGF-β)

Correct Answer: Interleukin-12 (IL-12)

Q11. Which hypersensitivity type is primarily mediated by antibodies binding to cell-surface antigens leading to complement activation and cell lysis?

• Type I (immediate, IgE-mediated)
• Type II (antibody-mediated cytotoxicity)
• Type III (immune complex-mediated)
• Type IV (delayed-type, T cell-mediated)

Correct Answer: Type II (antibody-mediated cytotoxicity)

Q12. Where do dendritic cells primarily present antigen to naïve T cells to initiate adaptive immune responses?

• Bone marrow
• Thymus medulla
• T cell zones of secondary lymphoid organs (e.g., lymph node paracortex, spleen white pulp)
• Mucosal epithelial surfaces only

Correct Answer: T cell zones of secondary lymphoid organs (e.g., lymph node paracortex, spleen white pulp)

Q13. The B cell receptor complex required for signal transduction consists of surface immunoglobulin non-covalently associated with:

• CD3 complex
• MHC class II molecules
• Igα (CD79a) and Igβ (CD79b)
• FcRn (neonatal Fc receptor)

Correct Answer: Igα (CD79a) and Igβ (CD79b)

Q14. Somatic hypermutation that increases antibody affinity occurs predominantly in which anatomical structure?

• Thymic cortex
• Primary lymphoid follicles in bone marrow
• Germinal centers of secondary lymphoid organs
• Peyer’s patch epithelium only

Correct Answer: Germinal centers of secondary lymphoid organs

Q15. Which laboratory assay quantifies the frequency of antigen-specific cytokine-secreting T cells at single-cell resolution?

• ELISA (enzyme-linked immunosorbent assay)
• Western blot
• ELISpot (enzyme-linked immunospot)
• Flow cytometry forward scatter only

Correct Answer: ELISpot (enzyme-linked immunospot)

Q16. Which immunoglobulin is the predominant isotype in systemic secondary immune responses and can cross the placenta to provide neonatal immunity?

• IgM
• IgA
• IgD
• IgG

Correct Answer: IgG

Q17. Neutralizing antibodies protect against viral infection primarily by:

• Activating complement to lyse infected host cells
• Blocking pathogen or toxin binding to host cell receptors
• Promoting somatic hypermutation in viruses
• Enhancing antigen presentation on MHC I

Correct Answer: Blocking pathogen or toxin binding to host cell receptors

Q18. Presentation of endogenous (intracellular) peptide antigens to CD8+ T cells is mediated mainly by which molecules?

• MHC class II molecules on professional APCs
• MHC class I molecules expressed on nearly all nucleated cells
• CD1 molecules presenting lipid antigens to CD8 cells
• Secreted antibodies bound to antigens

Correct Answer: MHC class I molecules expressed on nearly all nucleated cells

Q19. Negative selection of developing T cells to eliminate strongly self-reactive clones occurs predominantly in which location?

• Bone marrow stromal niches
• Thymic cortex mediated by cortical epithelial cells only
• Thymic medulla with AIRE-driven expression of tissue-restricted antigens
• Spleen red pulp

Correct Answer: Thymic medulla with AIRE-driven expression of tissue-restricted antigens

Q20. Affinity maturation of the antibody response is best described as:

• Clonal deletion of low-affinity B cells in the bone marrow
• Somatic hypermutation in germinal centers followed by selection of higher-affinity B cell clones by follicular dendritic cells and Tfh cells
• Isotype switching without changes in antigen-binding affinity
• Random mutation of T cell receptors in peripheral blood

Correct Answer: Somatic hypermutation in germinal centers followed by selection of higher-affinity B cell clones by follicular dendritic cells and Tfh cells

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