Q.27 RAG recombinase is responsible for the formation of specific immune receptors. This
process occurs in
(A)T cells & B cells
(B) Natural killer cells
(C) Macrophages
(D)Neutrophils
RAG recombinase drives V(D)J recombination to form diverse T-cell receptors (TCRs) and B-cell receptors (BCRs), essential for adaptive immunity. The correct answer to this immunology question is option (A) T cells & B cells.
Correct Answer
RAG1 and RAG2 proteins form a complex that initiates site-specific DNA breaks in immunoglobulin and TCR gene segments during lymphocyte development. This process exclusively occurs in developing T cells and B cells, enabling antigen-specific immune responses.
Option Breakdown
| Option | Description | Correct/Incorrect | Explanation |
|---|---|---|---|
| (A) T cells & B cells | Lymphocytes undergoing receptor gene rearrangement | Correct | RAG expression is restricted to pro-B, pre-B, pro-T, and pre-T stages for V(D)J recombination of BCRs and TCRs. |
| (B) Natural killer cells | Innate lymphoid cells with germline receptors | Incorrect | NK cells lack clonotypic receptors and do not perform V(D)J recombination, though some progenitors express RAG transiently without functional rearrangement. |
| (C) Macrophages | Phagocytic myeloid cells | Incorrect | Macrophages handle antigen presentation and phagocytosis but lack RAG and adaptive receptor genes. |
| (D) Neutrophils | Granulocytic innate immune cells | Incorrect | Neutrophils provide rapid antimicrobial responses via granules and NETs, without RAG-mediated recombination. |
