Adaptive control of innate immunity

Abstract

The mechanisms by which the immune system responds to an infection or disease depend on a complex interplay between the elements of innate and adaptive immunity. While most of the focus so far has been on the innate instruction of the adaptive immune responses, considerable evidence now suggests an equally important adaptive control of the innate immunity. Several studies yield new insights into how the adaptive immunity by initiating an antigen-specific response can compensate, suppress and activate innate responses at the site of tissue antigen. Here we discuss recent advances in our understanding of the adaptive control of immune effector functions in various pathological and physiological conditions.

Figure 1. T cell-NK cell cooperativity in tumour rejection

In the antigen (Ag) positive environment, if in the presence of activated T cells, NK cells are activated, complete tumour rejection ensues. If they fail to activate NK cells early enough, antigen escape variants develop and tumour is not rejected. In the antigen negative environment, in the absence of T cell activation, there is no tumour rejection. In the Ag+/- mix tumour environment, again if the activated T cells fail to activate NK cells early enough, there is no tumour rejection. When both the effectors are activated, there is complete tumour rejection.