Japanese cedar pollinosis and HLA-DP5.

Japanese cedar pollinosis is a type I allergic disease caused by Japanese cedar (Cryptomeria japonica) pollen. We investigated the association between the disease and HLA class II alleles by HLA-DNA typing using a PCR-SSOP method and found that the frequency of HLA-DP5 (DPA1*02022 and DPB1*0501) was significantly increased in the patients. To investigate whether the HLA-DP5 molecule is directly involved in the pathogenesis of the disease, Japanese cedar pollen antigen (CPAg)-specific T cell lines were established from 3 patients who possessed HLA-DP5 (DPA1*02022/ DPB1*0501). By using these CPAg-specific T cell lines and HLA class II-expressing L-cell transfectants, we found that disease-associated HLA-DP5 restricted T cells specific for CPAg existed in the patients. Furthermore, among 38 synthesized overlapping peptides spanning the entire length of one of the major Japanese cedar pollen allergens, Cry j 1, an immunodominant peptide which induced HLA-DP5 restricted Th2 was identified. These observations suggest that the HLA-DP5 may be involved, at least in part, in the pathogenesis, by helping the IgE antibody production against CPAg.