# DBT JRF 2020 — Question 1

Exam: DBT JRF 2020 · Section: B · Topic: Immunology · Difficulty: Easy

## Question

The innate immune system recognizes Pathogen Associated Molecular Patterns (PAMPs) through activation of

## Options

- **A.** B cell receptor
- **B.** T cell receptor
- **C.** Toll-like receptor
- **D.** Fc receptor

## Answer

Option C

## Explanation

Toll-like receptors (TLRs) are transmembrane pattern recognition receptors (PRRs) of the innate immune system. They recognise conserved microbial structural motifs called Pathogen-Associated Molecular Patterns (PAMPs): TLR4 → LPS (Gram-negative bacteria); TLR2 → peptidoglycan and lipoteichoic acid; TLR5 → flagellin; TLR9 → unmethylated CpG DNA (bacteria/viruses); TLR3 → dsRNA (viruses). TLR signalling via adaptor proteins (MyD88, TRIF) activates NF-κB and IRFs, inducing pro-inflammatory cytokines (TNF-α, IL-6, IL-12) and interferons. B cell receptors (BCR) and T cell receptors (TCR) are adaptive immunity components that recognise specific antigens.

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