STRESS PROTEINS - SELF, NON-SELF AND THE IMMUNE-RESPONSE

The induced expression of the heat shock gene family is a universal response to cellular stresses such as elevated temperature of oxidative injury. The constitutive expression and evolutionarily conserved nature of heat shock proteins (HSP) suggest that they also play essential roles during normal cellular functions. The expression of HSP in both prokaryotic and eukaryotic cells and their conserved structure is relevant to HSP-specific T cell activation and provides a link between the immune response to infection (immune surveillance, the immune response to non-self) and auto-immunity (cross-reactivity to self-HSP). HSP are potent immunogens for both cytotoxic and helper T cells and promote the activation of gamma delta T cells. These latter cells localize within the epithelia, where encounter between host and pathogens first occurs, and may thus play a role in early immune defences. The intervention of HSP as potential protectors (of host cells [self] or alternatively, of pathogens [non-self]) is suggested by their functions in protein-protein interactions. This <<molecular chaperoning>> prevents aggregation of denatured proteins and misassembly of nascent peptides and contributes to molecular transport and translocation across cellular membranes. HSP may also <<chaperone>> antigens and thus participate in antigen processing and presentation.