What activates T-cells?

What activates T-cells?

• A. When innate pattern recognition receptors recognize microbial components.
• B. When an antigen binds to its receptors.
• C. When antibodies bind to antigen.
• D. When cytokines activate B cells to present antigens.

Answer: (B)

T cell activation relies on the T cell receptor recognizing a specific peptide antigen presented by an MHC molecule on an antigen-presenting cell, with a necessary co-stimulatory signal to fully activate. This means the antigen must be displayed in the context of MHC and engage the TCR, not merely bind free antigen. The statement describing antigen binding to its receptor captures this triggering interaction, as it reflects the need for specific recognition of a peptide-MHC complex by the TCR. Innate pattern recognition drives innate responses (not T cell activation directly), antibodies binding to antigen mainly activate B cells and effector functions, and cytokines helping B cells present antigen involve B-cell pathways rather than direct T-cell activation.

T cell activation relies on the T cell receptor recognizing a specific peptide antigen presented by an MHC molecule on an antigen-presenting cell, with a necessary co-stimulatory signal to fully activate. This means the antigen must be displayed in the context of MHC and engage the TCR, not merely bind free antigen. The statement describing antigen binding to its receptor captures this triggering interaction, as it reflects the need for specific recognition of a peptide-MHC complex by the TCR. Innate pattern recognition drives innate responses (not T cell activation directly), antibodies binding to antigen mainly activate B cells and effector functions, and cytokines helping B cells present antigen involve B-cell pathways rather than direct T-cell activation.