Q.40

Match the cell types listed in Group I with associated processes listed in Group II.

Introduction

In competitive exams, questions that ask you to match immune cell types with their characteristic functions are common and highly scoring. Understanding which cells mediate antibody production, histamine release, early recruitment to infection sites and antibody‑dependent cell‑mediated cytotoxicity helps to quickly eliminate wrong options.​

Step‑by‑step matching of Group I and Group II

Group I:
(p) NK cells
(q) B cells
(r) Mast cells
(s) Neutrophils

Group II:
(i) Antibody production
(ii) First cells to be recruited at the site of infection
(iii) Antibody‑dependent cell‑mediated cytotoxicity (ADCC)
(iv) Histamine production

1. NK cells (p)

   • NK cells are large granular lymphocytes of innate immunity that kill virus‑infected and tumor cells.​

   • They express Fc receptor CD16 and are the primary mediators of antibody‑dependent cell‑mediated cytotoxicity (ADCC), in which they bind antibody‑coated targets and induce apoptosis.​

   • So, (p) NK cells → (iii) ADCC.

2. B cells (q)

   • B lymphocytes differentiate into plasma cells that synthesize and secrete antigen‑specific antibodies, forming a core part of adaptive humoral immunity.​

   • Thus, (q) B cells → (i) Antibody production.

3. Mast cells (r)

   • Mast cells are connective‑tissue sentinel cells packed with granules rich in histamine and other mediators.​

   • On activation (for example via IgE cross‑linking), they degranulate and release histamine, driving vasodilation and acute allergic responses.​

   • Hence, (r) Mast cells → (iv) Histamine production.

4. Neutrophils (s)

   • Neutrophils are the most abundant circulating granulocytes and are rapidly recruited as the first responders to sites of acute infection or tissue injury.​

   • They phagocytose microbes and release reactive oxygen species and enzymes to kill pathogens.​

   • Therefore, (s) Neutrophils → (ii) First cells to be recruited.

The final pattern is:
(p)–(iii), (q)–(i), (r)–(iv), (s)–(ii) → Option (C).

Detailed explanation of each option

Option (A): (p)–(ii); (q)–(i); (r)–(iii); (s)–(iv)

• NK cells as “first cells recruited at the site of infection” is incorrect; neutrophils are the classic first responders of acute inflammation.​

• Assigning ADCC to mast cells is wrong; ADCC is mainly mediated by NK cells via Fc receptor CD16.​

• Neutrophils are not the main histamine‑producing cells in basic immunology questions, even though they can produce some histamine under special conditions.​

Option (B): (p)–(ii); (q)–(i); (r)–(iv); (s)–(iii)

• NK cells again are wrongly linked to early recruitment rather than ADCC.​

• Neutrophils do not primarily mediate antibody‑dependent cell‑mediated cytotoxicity in standard exam contexts; this role is characteristic of NK cells.​

Option (C): (p)–(iii); (q)–(i); (r)–(iv); (s)–(ii) – Correct

• NK cells → ADCC: they kill antibody‑coated target cells using perforin and granzymes.​

• B cells → antibody production: plasma cells derived from B cells secrete antigen‑specific antibodies.​

• Mast cells → histamine production: their cytoplasmic granules are rich in histamine, released during degranulation.​

• Neutrophils → first cells recruited: they are rapidly mobilized to the infection site during acute inflammation.​

Option (D): (p)–(iii); (q)–(ii); (r)–(i); (s)–(iv)

• B cells do not function as the first cells recruited to infection sites; that role belongs to neutrophils.​

• Mast cells are not the principal antibody‑producing cells; that is the function of B‑cell‑derived plasma cells.​

Quick revision table: immune cell types and key functions