T cell responses to conserved bacterial heat-shock-protein epitopes induce resistance in experimental autoimmunity.

The relationships between bacterial heat shock proteins (HSPs) and autoimmunity were first disclosed in the mycobacteria-induced model of adjuvant arthritis: passive transfer of a T cell clone responding to mycobacterial HSP60 evoked disease in naive recipient animals. However, the disease could not be induced by immunization with HSP60, but instead protection was established. Subsequently, similar protection was found in experimental models of arthritis that do not involve challenge with bacterial antigens for the induction of disease. This rather general protective potency of bacterial HSPs against arthritis seems to result from the capacity of strongly conserved sequences in the protein to activate T cells that cross-recognize the mammalian homologous HSP-sequences presented on cells at the site of inflammation. It is possible that immunological recognition of bacterial HSPs is part of a general strategy used by the immune system for the regulatory control of the potentially harmful recognition of autoantigens as a hedge against the development of autoimmune disease.