Question

explain how naive T cells become sensitized to an antigen

Answer 1

Sensitisation is the process of conversion of naive T cell to mature effector T cell. This process of activation of T cell involves a process of signal transduction and involves 2 steps to become completely active:

First signal: this is antigen specific and involves the interaction of T cell receptor with MHC (major histocompatibility complex) on the membrane of antigen presenting cells (APC). This is the stimulation step.

Secondary signal: a secondary signal that involves the co-stimulatory signal is antigen nonspecific and is provided by the interaction between co-stimulatory molecules (CD28 is present on the TCR of naive T cell and interacts with the ligand CD80 and CD 86 which are present on the APC ). This general interactive step leads to the proliferation and differentiation of T cell into either cytotoxic T cell or helper T cell. Activationof T cells without co-stimulation may lead to T cell anergy, T cell deletion or the development of immune tolerance.