Identification of Dermatophagoides farinae-2-derived peptides and class II HLA molecules recognized by T cells from...

Der f2, the group 2 allergen of Dermatophagoides farinae, is one of the major inhalation allergens in Japan. Using the mixture of a panel of overlapping synthetic peptides that spread over the entire Der f2 molecule, we found that polyclonal Der f2-specific short-term T cell lines prepared from peripheral blood mononuclear cells of 5 individuals allergic to Der f who carry most of the common HLA haplotypes seen in the Japanese population can respond mainly to 7 different peptides. Distribution of the T cell epitopes on Der f2 was not identical with that on Der p2. Five of 7 peptides stimulated T cells of more than 2 donors, regardless of HLA types. Inhibition patterns by anti-HLA class II mAbs were heterogenous in proliferative responses of each cell line, three were mainly inhibited by anti-HLA-DR mAb, and the others were inhibited by anti-HLA-DQ mAb. One of these T cell lines, SM, of which the proliferative response was partially inhibited by anti-HLA-DQ mAb, was cloned. Indeed, the T cell clone SM4.6 was restricted by DQ6 molecules encoded for by an HLA-DRB1*1502-DRB5*0102-DQA1*0103-DQB1*0601 haplotype. These results indicate that patients' T cells recognize Der f2 in association with a variety of HLA-DR or HLA-DQ as antigen-presenting molecules. Thus, although some peptides do have a more potent T cell stimulatory activity than others, the TCR ligands formed with the Der f2 molecule are highly heterogeneous, a factor also noted in Der f1-specific T cell lines in our previous study.