Types of immune responses MCQs With Answer

Types of immune responses MCQs With Answer

This quiz set is designed for M.Pharm students to deepen understanding of the different types of immune responses, their cellular and molecular mechanisms, and clinical implications. It covers innate versus adaptive immunity, humoral and cell‑mediated arms, primary and secondary responses, active and passive immunity, and specialized pathways such as Th1/Th2/Th17 polarization, complement activation, and antibody‑dependent cellular cytotoxicity. Each question emphasizes mechanistic detail relevant to pharmacology and immunotherapy, including key cytokines, receptor interactions, antigen presentation, and vaccine responses. Use these MCQs to test conceptual clarity and prepare for advanced coursework, research, and clinical application in immunotechnology.

Q1. Which statement best characterizes innate immunity compared to adaptive immunity?

• Rapid, non‑specific response mediated by germline‑encoded receptors with no memory
• Slower, antigen‑specific response that generates long‑lived memory cells
• Requires prior immunization to become activated
• Relies solely on antibody production by B cells

Correct Answer: Rapid, non‑specific response mediated by germline‑encoded receptors with no memory

Q2. Which pairing correctly matches the primary effector cell with the corresponding immune response type?

• B cells — cell‑mediated immunity
• CD8+ T cells — humoral immunity
• B cells — humoral immunity
• Macrophages — antibody class switching

Correct Answer: B cells — humoral immunity

Q3. What distinguishes a secondary (memory) immune response from a primary immune response?

• Slower onset with lower peak antibody titer
• Faster onset with higher affinity antibodies and greater IgG predominance
• Only IgM is produced during secondary responses
• Memory responses are always cell‑mediated and never humoral

Correct Answer: Faster onset with higher affinity antibodies and greater IgG predominance

Q4. Active immunity differs from passive immunity in that active immunity:

• Is conferred by transfer of preformed antibodies from another individual
• Is immediate and short‑lived without memory cell generation
• Requires the host’s immune system to recognize antigen and generate memory cells
• Can only be achieved through monoclonal antibody therapy

Correct Answer: Requires the host’s immune system to recognize antigen and generate memory cells

Q5. Which cytokine profile and outcome is most characteristic of a Th1‑polarized immune response?

• IL‑4, IL‑5 production leading to eosinophil activation and IgE class switching
• IFN‑γ production enhancing macrophage activation and CD8+ T cell responses
• IL‑10 dominated anti‑inflammatory response promoting tolerance
• TGF‑β and IL‑6 inducing neutrophil recruitment at mucosal surfaces

Correct Answer: IFN‑γ production enhancing macrophage activation and CD8+ T cell responses

Q6. Which immunoglobulin is the principal mediator of mucosal immunity and is abundant in secretions?

• IgG
• IgM
• IgA
• IgE

Correct Answer: IgA

Q7. Presentation of endogenous (intracellular) antigen peptides to CD8+ cytotoxic T lymphocytes is primarily mediated by:

• MHC class II molecules on professional antigen‑presenting cells
• MHC class I molecules expressed by almost all nucleated cells
• Complement receptors on macrophages
• Fc receptors on B cells

Correct Answer: MHC class I molecules expressed by almost all nucleated cells

Q8. Which role is a major function of the complement system in immune responses?

• Direct transcriptional activation of T cell cytokine genes
• Opsonization of pathogens and formation of membrane attack complex causing lysis
• Induction of immunological memory in B cells
• Exclusive regulation of antibody class switching

Correct Answer: Opsonization of pathogens and formation of membrane attack complex causing lysis

Q9. Pattern recognition receptors (PRRs) such as Toll‑like receptors (TLRs) detect microbial patterns known as:

• Autoantigens
• Hapten complexes
• Pathogen‑associated molecular patterns (PAMPs)
• Major histocompatibility complexes

Correct Answer: Pathogen‑associated molecular patterns (PAMPs)

Q10. Antibody‑dependent cellular cytotoxicity (ADCC) is primarily mediated by:

• B cells recognizing antigen through BCR and lysing targets directly
• NK cells binding IgG Fc via CD16 (FcγRIII) to kill antibody‑coated target cells
• Complement C3b alone lysing target cells without cellular involvement
• Neutrophils producing IgE to mediate cytotoxicity

Correct Answer: NK cells binding IgG Fc via CD16 (FcγRIII) to kill antibody‑coated target cells

Q11. The clonal selection theory of adaptive immunity states that:

• All lymphocytes are identical and change specificity after antigen exposure
• Antigen selectively activates pre‑existing lymphocyte clones bearing specific receptors, which then expand
• Memory cells are formed only by macrophages after phagocytosis
• Clonal deletion occurs exclusively in peripheral tissues after infection

Correct Answer: Antigen selectively activates pre‑existing lymphocyte clones bearing specific receptors, which then expand

Q12. Affinity maturation of antibodies occurs primarily through which mechanism and anatomical site?

• Class switch recombination in the bone marrow without mutation
• Somatic hypermutation in germinal centers of lymph nodes and spleen
• V(D)J recombination in peripheral tissues post antigen exposure
• Complement activation in the thymus

Correct Answer: Somatic hypermutation in germinal centers of lymph nodes and spleen

Q13. Isotype (class) switching in B cells requires which critical interactions or signals?

• Antigen binding alone without T cell help
• CD40‑CD40L interaction with cytokine signals from helper T cells
• Direct signaling from NK cells via perforin
• Complement deposition on the B cell receptor

Correct Answer: CD40‑CD40L interaction with cytokine signals from helper T cells

Q14. Which description best contrasts memory B cells and plasma cells?

• Memory B cells secrete large amounts of antibody continuously; plasma cells do not secrete antibody
• Plasma cells are long‑lived and do not produce antibodies; memory B cells are short‑lived antibody factories
• Memory B cells persist to provide rapid secondary responses; plasma cells are antibody‑secreting effectors that may be short‑ or long‑lived
• Both are identical in function and lifespan

Correct Answer: Memory B cells persist to provide rapid secondary responses; plasma cells are antibody‑secreting effectors that may be short‑ or long‑lived

Q15. Immediate hypersensitivity (Type I) reactions are primarily mediated by which immunological components?

• IgE bound to mast cells and basophils releasing histamine and mediators
• Immune complexes activating complement causing vasculitis
• CD8+ T cell cytotoxicity against host cells
• Autoantibody‑mediated complement lysis of red blood cells exclusively

Correct Answer: IgE bound to mast cells and basophils releasing histamine and mediators

Q16. Natural killer (NK) cells differ from cytotoxic CD8+ T lymphocytes in that NK cells:

• Require antigen presentation by MHC class I to recognize targets
• Recognize and kill cells with downregulated or missing MHC class I via ‘missing‑self’ recognition without prior sensitization
• Undergo somatic hypermutation to increase receptor diversity
• Are B cell derivatives involved in antibody production

Correct Answer: Recognize and kill cells with downregulated or missing MHC class I via ‘missing‑self’ recognition without prior sensitization

Q17. Fc receptors (FcRs) on effector cells contribute to immune responses by:

• Presenting peptide antigens on MHC molecules
• Mediating phagocytosis, opsonization, and ADCC through binding the Fc portion of antibodies
• Directly catalyzing V(D)J recombination in B cells
• Inhibiting complement activation exclusively

Correct Answer: Mediating phagocytosis, opsonization, and ADCC through binding the Fc portion of antibodies

Q18. Which vaccine type typically induces the most balanced and long‑lasting humoral and cellular immunity similar to natural infection?

• Inactivated (killed) whole‑cell vaccines
• Subunit protein vaccines without adjuvant
• Live attenuated vaccines
• Passive antibody administration

Correct Answer: Live attenuated vaccines

Q19. Differentiation of naïve CD4+ T cells into Th17 cells is promoted mainly by which combination of cytokines?

• IL‑12 and IFN‑γ
• IL‑4 and IL‑5
• TGF‑β together with IL‑6 (and IL‑23 for stabilization)
• IL‑2 and IL‑10 only

Correct Answer: TGF‑β together with IL‑6 (and IL‑23 for stabilization)

Q20. Central tolerance mechanisms that prevent autoimmunity primarily occur in which sites and by which process?

• Peripheral tissues via regulatory T cell suppression exclusively
• Thymus and bone marrow by deletion (negative selection) of strongly self‑reactive lymphocyte clones
• Lymph nodes by affinity maturation eliminating autoreactive B cells
• Spleen by complement‑mediated lysis of self‑reactive cells

Correct Answer: Thymus and bone marrow by deletion (negative selection) of strongly self‑reactive lymphocyte clones

Download