Birch pollen is a very common cause of nasal
allergy (
pollinosis) not only in Scandinavia, Europe, Canada, and the northern part of the United States but also in Hokkaido, Japan. We have previously reported a positive association between the
HLA-DR9 phenotype and the development of birch
pollen allergy in Japanese subjects. However, there is little information about
T cell epitopes of birch pollen which are presented by HLA class II molecules other than
HLA-DR9. Therefore, we analyzed the difference in
T cell epitope usage in patients who had
HLA-DR9 versus those who did not. Seven Japanese patients with birch
pollinosis were studied. Some groups of
peptides representing
T cell epitopes (Betula verrucosa; Bet VI
peptides, p7-33,
p23-46, p138-160) appeared to be shared by the majority, while another
peptide (Bet VI p72-95) was recognized predominantly by patients who expressed
HLA-DR9 and/or
HLA-DQ3 molecules. Moreover, seven T cell clones and eight T cell lines were generated from two patients who did not have
HLA-DR9 or
HLA-DQ3. Using some of these T cell clones/lines, we investigated the relationship between HLA class II molecules and antigenic
peptides. One of these T cell clones recognized antigenic
peptides in the context of the
HLA-DQ1 molecule. To our knowledge, this is the first indication that the
epitope on Bet VI can be presented by the
HLA-DQ molecule.