What is the function of CD25 in T cells?

The correct answer highlights the essential role of CD25 in T cells, particularly in the context of T cell activation and proliferation. CD25 is the alpha chain of the interleukin-2 receptor (IL-2R). When T cells are activated, especially in response to antigens, they express CD25. This chain allows T cells to bind interleukin-2 (IL-2), a pivotal growth factor produced by T cells themselves, which promotes their proliferation and survival.

CD25's presence signifies that the T cell is in an active state and ready to respond to inflammatory signals. By enhancing the T cell's response to IL-2, CD25 facilitates clonal expansion of T cells after activation, ultimately contributing to a robust immune response. Thus, the contribution of CD25 to T cell activation and proliferation is vital for effective immune function, particularly during infections or other immune challenges.

The other concepts mentioned in the other options do not accurately describe the function of CD25. CD25 is not a receptor for bacterial antigens, nor is it directly involved in the production of antibodies. While there are mechanisms in the immune system that involve the inhibition of T cell activity during infection, CD25 itself does not serve this function; instead,