vaccines extra reading Flashcards
adjuvents and t cell link?
In Chapter 6 , we mentioned the essential role of adjuvants in inducing primary T cell responses to protein antigens such as vaccines. Many adjuvants are products of microbes or mimic molecules produced by microbes and necrotic cells and thus elicit innate immune responses. One of the major functions of adjuvants in T cell activation is to stimulate the expression of B7 costimulators on APCs.
Unactivated, or resting, APCs in normal tissues are capable of presenting self antigens to naive T cells, but because these tissue APCs express only low levels of costimulators, potentially self-reactive T cells that see the self antigens are not activated and may be rendered permanently unresponsive (see Chapter 15 ). Regulatory T cells, which are important for tolerance to self antigens (see Chapter 15 ), are also dependent on B7:CD28-mediated costimulation for their generation and maintenance. It is possible that the low levels of B7 costimulators that are constitutively expressed by resting APCs function together with the self antigens that are displayed by these APCs to maintain regulatory T cells.
