A PATIENT-DERIVED CYTOTOXIC T-LYMPHOCYTE CLONE AND 2 PEPTIDE-DEPENDENT MONOCLONAL-ANTIBODIES RECOGNIZE HLA-B27-PEPTIDE COMPLEXES WITH LOW STRINGENCY FOR PEPTIDE SEQUENCES

HLA-B27 molecules expressed on the T2 mutant cell line do not have pep tides, Such empty HLA-B27 molecules were not recognized by an HLA-B27- restricted cytotoxic T-lymphocyte (CTL) clone (auto-1) derived from sy novial fluid. To test for peptide dependency of the clone, B27-T2 cell s were incubated with a panel of 48 synthetic peptide nonamers in whic h P2 was arginine, Target cell lysis was induced by seven completely d ifferent peptides, This lack of stringency was compared with that of a peptide-dependent monoclonal antibody B27.M2. Positive B27.M2 reactiv ity resulted when the B27-T2 cells were incubated with two peptides: R RKAMFEDI and RRMGPPVGHR, derived from Chlamydia HSP60 and human ribonu cleoprotein, respectively, Because of the limited availability of CTL versus monoclonal antibody, the specificity of B27.M2 was studied in g reater detail, The importance of the HLA-B27 heavy chain in antibody r ecognition of class I-peptide complexes was demonstrated by site-direc ted mutagenesis. The stringency of the peptide residues was tested by making analogs of each of the nine residues in RRKAMFEDI, creating a p anel of 180 analogs. Although stringency was highest for the sixth pos ition, as many as six different amino acids provided positive reactivi ty. These results indicate that immune recognition of HLA-B27-peptide complexes might have rather low stringency for the peptide sequences. In theory, then, pathogen-derived peptides which induce autoimmunity b y generating autoreactive CTL might not share much sequence similarity with the responsible self peptides.