Subtopic: Fundamentals of Downstream processing (chromatography, filtration)
Question Statement:
Dendritic cells are involved in cross-presentation of antigens. Which of the
following protein(s) is(are) required for cross-presentation?
P. Basic leucine zipper ATF-like transcription factor 3 (BATF3)
Q. Membrane associated ring-CH-type finger 1 (MARCH-1)
R. Solute carrier family 10 member 1 (SLC10A1)
S. Class II-associated invariant chain peptide (CLIP)
Options:
(A) P only
(B) P and R only
(C) P, Q and R only
(D) S only
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2023 Q.17)**
**1. Governing Concept**:
- **Topic**: Immunology & Antigen Presentation (Cross-Presentation)
- **Cross-presentation** is the specialized immunological mechanism wherein **dendritic cells (DCs)** internalize exogenous extracellular antigens (e.g., from virally infected cells or tumor cells) and route them onto **MHC class I molecules** to activate and prime naive **CD8+ cytotoxic T lymphocytes (CTLs)**.
**2. Option Analysis**:
- **Option (A) [exogenous antigens on MHC-I to activate CD8+ T-cells] is CORRECT**: Canonical textbook definition of cross-presentation.
- **Option (B) is INCORRECT**: Presenting exogenous antigens on MHC-II to CD4+ T-cells is standard classic antigen presentation, not cross-presentation.
- **Option (C) is INCORRECT**: Endogenous antigens are normally presented on MHC-I, not cross-presented.
- **Option (D) is INCORRECT**: Endogenous antigens on MHC-II is non-standard autophagy presentation.
**3. Final Answer**:
- **Correct Choice**: **A**
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