Fig. 1

A DRB1 or DRB5 alleles associated with the presence of anti-topo I antibody in various ethnicities and their amino acid sequence at positions 67–71 in the third hypervariable region (HVR). B Proliferative responses of a representative topo I-reactive CD4⁺ T cell clone derived from an anti-topo I-positive patient with SSc in the presence of antigenic peptide-pulsed L cell transfectants expressing a series of human HLA-DR molecules harboring the DRB1 or DRB5 alleles associated with the presence of anti-topo I antibody. The peptide-induced T cell proliferation was measured by ³H-thymidine incorporation