Immunity and inflammation: the cosmic view

This paper presents an overview of the evolution of defence reactions in multicellular animal life. The co-evolution of hosts and pathogens provides the context to describe the major features of defence reactions and the countermeasures they evoke in their targets. Three major types of solutions to the riddle of self-non-self discrimination are discussed briefly: non-clonal recognition mediated by lectins, the preferential accumulation of C3 in microbial surfaces and vertebrate clonal immunity. Vertebrate immunity is described as a specialized type of inflammation against infectious agents that evolved in response to countermeasures successfully used by intracellular pathogens against non-specific defences.