B-CELL EPITOPES RECOGNIZED BY IGE FROM PATIENTS SENSITIVE TO AMB A-5

Background The response to allergens characterized by IgE-mediated hyp ersensitivity is selective. The search for the inherited contribution to atopy has among other things, focused on the linkage of sensitivity to the presence of specific alleles in the DR and DQ locus. More than 90% of the responders to Amb a 5, an allergen from ambrosia artemisif olia, are DR-2 positive. This relationship is logically linked to the T-cell epitope presentation by the HLA complex. Objectives This study aims to investigate a possible relationship between T-cell epitopes, B -cell epitopes and the alleles of the DR and DQ loci in Amb a 5 sensit ive DR-2+ and DR-2-individuals. Methods Inhibition of solid state Elis a assays by IgE-enriched and IgG-depleted, heated sera. The inhibition was carried out in checkerboard pattern, bidirectionally; A inhibits B and B inhibits A. Results The B-cell epitopes defined by the inhibit ion pattern were all found to be conformational. Three different epito pe patterns (A, B, C) were recognized. The IgE and IgG complexes were found in only one responder. The DR and DQ locus alleles were all sequ enced. Although all the individuals studied responding to Amb a 5 show presence of alleles such as 1501, associated with DR-2, our data indi cates no correlation between the B-cell epitopes recognized and the DR and DQ locus alleles. A well known, general T-cell motif was recogniz ed in the known sequence of Amb a 5. Conclusions Our investigation sug gests that the choice of B-cell recognition is regulated independently of a putative link between T-cell epitope recognition and the D locus .