Question

Which of the following is(are) involved in the activation of cytotoxic T cells?

• A. MHC I
• B. FcR
• C. T cell receptor
• D. CTLA 4

Hint:

Cytotoxic T cells are activated when their TCR binds to an antigen presented by MHC I molecules on infected cells.

Answer 1

The Correct Option is A, C

Step 1: Understanding the activation of cytotoxic T cells. 
Cytotoxic T cells are activated when their T cell receptor (TCR) recognizes an antigen presented by MHC I molecules on the surface of infected cells. This interaction is crucial for the activation of cytotoxic T cells and their ability to kill infected or cancerous cells. 
 

Step 2: Analyzing the options. 
- (A) MHC I: Correct — MHC I molecules present antigens to cytotoxic T cells, activating them. 

- (B) FcR: Incorrect — Fc receptors are involved in the immune response of other cells like macrophages and B cells, not T cell activation. 

- (C) T cell receptor: Correct — The T cell receptor on cytotoxic T cells recognizes antigens presented by MHC I molecules. 

- (D) CTLA 4: Incorrect — CTLA 4 is a negative regulator of T cell activation, inhibiting T cell responses rather than promoting them. 
 

Step 3: Conclusion. 
The correct answer is (A) MHC I, (C) T cell receptor.