Question

The requirement of costimulatory signal to induce the activation of T cells upon antigen encounter which originally has evolved to prevent autoimmune attack by T cells, may act as a stumbling block for anti-tumor immune function. Explain how it is so.

Answer 1

Co-stimulatory molecules are responsible for amplification of T cell response after their interaction with antigen/ MHC. These co stimulatory signals helps T cell differentiation .They play a very crucial role in T cell activation, subset differentiation, effector function and survival. Cancerous cells though sometimes produce altered self antigens , in major cases they express normal self antigens in higher amount and thereby promotes cell proliferation. As co stimulatory signals prevent T cells to recognize self antigens, these highly expressed self antigens are not detected as foreign antigens. This becomes a problem as they are not recognized as foreign and no immune response is developed against them.