CROSSRECOGNITION BY CD8 T-CELL RECEPTOR-ALPHA-BETA CYTOTOXIC T-LYMPHOCYTES OF PEPTIDES IN THE SELF AND THE MYCOBACTERIAL HSP60 WHICH SHARE INTERMEDIATE SEQUENCE HOMOLOGY

Immunization of C57BL/6 mice with the mycobacterial heat shock protein (hsp) 60 in immunostimulating complexes caused the in vivo activation of autoreactive histocompatibility complex class I (H-2D(b))-restrict ed CD8 T cell receptor (TcR) alpha/beta cells. A CD8 TcR alpha/beta cl one with specificity for the mycobacterial hsp60 peptide(499-508) was derived from this immunization,which, in addition, recognized syngenei c macrophages which had been stressed by interferon-gamma (IFN-gamma) stimulation. The stress-induced, self peptide could be extracted from IFN-gamma-stressed macrophages by acid elution, suggesting that the IF N-gamma-induced self peptide is derived from an endogenous protein. Ba sed on our observation that lysis of stressed target cells by this cyt otoxic T lymphocyte (CTL) clone was specifically inhibited by hsp60-sp ecific antisense oligonucleotides, we used synthetic peptides represen ting amino acid (aa) sequences of the murine hsp60 for target cell sen sitization and identification of the relevant self peptide. Synthetic peptides representing 9-mer to 11-mer aa sequences of the murine hsp60 with asparagine in anchor position 4 or 5 as the minimal requirement for H-2D(b) binding were tested in CTL assays. The overlapping murine hsp60 peptides(162-170/171) were stimulatory at a concentration as low as 10-100 pM. Seven other peptides of the murine hsp60 required inter mediate peptide concentrations of 10-100 nM for recognition by the CTL clone. Although the murine and mycobacterial hsp60 peptides recognize d by this CTL clone showed only intermediate homology (3 identical and 3 similar aa), our data suggest that endogenous hsp60 itself is the s ource of self peptide(s) presented by IFN-gamma-stressed macrophages t o the cross-reactive CTL clone with promiscuous specificity. This noti on is consistent with the idea of hsp as a link between infection and autoimmunity.