Question

activated T cells express __ which bind B7 with 20x higher affinity for B7 than CD28; results in __ of T cell activity and proliferation

Answer 1

Activated T cells express CTLA-4, which binds B7 with higher affinity than CD28, leading to the downregulation of T cell activity and proliferation, providing crucial regulation of the immune response.

Step-by-step explanation:

Activated T cells express CTLA-4, which binds to B7 with 20x higher affinity than CD28, resulting in the downregulation of T cell activity and proliferation. CTLA-4 acts as a checkpoint in the immune response, serving as a mechanism of immune regulation to prevent overactivation, which could potentially lead to autoimmunity. Whereas the T cell receptor (TCR) is responsible for the recognition of antigenic peptides presented by APCs, the function of CTLA-4 as a negative regulator is essential to maintain immune homeostasis.