Background: We have recently described the association between the IgE antibody response to Ole e I (the major antigen from olive tree pollen) and the DR7-DQ2 haplotype in a Spanish population.
Objective and methods: Due to the linkage disequilibrium between DR7 and DQ2, and thus the difficult distinction between the role of these two antigens in the T-cell activation response, we decided to solve this question by two approaches: 1. The study of another ethnic group, individuals of Arabic origin, with a presumably distinct disequilibrium linkage between DR and DQ antigens. Genomic DNA typing was performed in 46 subjects (allergic and non-allergic) by Restriction Fragment Length Polymorphism (RFLP) and results showed that patients with specific IgE antibodies alpha-Ole e I, were DR7 and/or DQ2. These data show a similar restriction pattern to those previously described for Spanish patients. The phenotypic frequency of DR7 antigen is significantly greater than in the non-allergic population, with a corrected P (Pc) value of 0.03. 2. The analysis of the genetic requirements of Ole e I response, using T-cell lines specific for this antigen. This was first carried out by blocking the proliferative response of these T-cell lines with specific anti-human HLA class II antibodies and then testing the genetic restriction of this response using a panel of histocompatible and histoincompatible Antigen Presenting Cells (APCs). Both experiments corroborate the hypothesis that DR7 and DQ2 are implicated in the recognition of Ole e I.