ASSOCIATION BETWEEN IGE RESPONSE AGAINST BET-V-I, THE MAJOR ALLERGEN OF BIRCH POLLEN, AND HLA-DRB ALLELES

The association of the human IgE response against Bet v I, the major allergen of birch pollen, and the HLA-DR and DQ phenotype was studied. Birch pollen allergic patients showed a typical case history, positive skin-prick test, and positive RAST with birch pollen extracts. They were divided into two groups. Group I (n = 37) consisted of individuals generating IgE antibodies that selectively reacted with Bet v I. Their serum IgE did not react with minor allergens from birch pollen as tested by immunoblot analysis, nor did they show a response against allergens from a panel of grass and other tree pollen or perennial allergens from animals and fungi as determined by skin-prick test. Patients belonging to group II (n = 34) possessed IgE reacting with Bet v I plus one or more additional allergens. The control group consisted of 637 healthy blood donors. Comparison of the frequencies of RFLP-defined HLA-DR and DQ alleles in patients and the control group revealed that the distribution of DRB3 alleles in group I patients differed significantly from that in the control group: A higher frequency of the DRw52a/c alleles in comparison to the control group (P(corr) < 0.02) was observed. In addition, alleles defined by nucleotide sequences coding for the amino acid sequence tyrosine-phenylalanine-histidine at positions 30-32 of the beta-chain of DR molecules were found with a higher frequency in patient group I(P(corr) < 0.02), too. These alleles comprise DRw52a/c and some DRB1 alleles. In patients of group II, no significant differences in the distribution of class II alleles in comparison with the control group were observed. The fact that the association with DRB alleles is observed only in patients with a selective allergen-specific IgE response could mean that, among the genes that contribute to disease susceptibility, the class II genes play a more dominant role in these patients. In conclusion, certain alleles encoded in DRB3 and DRB1 genes of the HLA complex might play a functional role in birch pollen allergy.