Innate and adaptive immunity

Abstract

Innate immune responses recognise generic targets on pathogens using germline encoded receptors, whereas adaptive immune responses recognise specific targets using randomly generated receptors which have an essentially unlimited recognition repertoire. Interactions between innate and adaptive forms of immune recognition are increasingly being recognised as essential for the effective functioning of the immune response. Examples given here demonstrate the advantages of integrating pre-programmed recognition (rapid response using widely distributed receptors) with random repertoire recognition (open repertoire for specific recognition of novel targets, with memory). The randomly generated repertoire brings problems of self/non-self discrimination, which is solved at multiple levels in the human immune system, including shaping of the naïve repertoire, stringent control of naïve cell activation by innate immune receptor recognition, and control by regulatory cells in the periphery. The interactions between innate and adaptive immunity are many, complex, and bidirectional, with innate mechanisms being instrumental in the initiation of adaptive responses, and controlling the type of adaptive response induced; innate effector mechanisms are also recruited in the effector phase of adaptive responses. The challenge is now to abstract the essential components of the innate-adaptive interaction in order to utilise this concept in alternative contexts.