FUNCTIONAL-HETEROGENEITY OF HUMAN T-CELL CLONES FROM ATOPIC AND NONATOPIC DONORS

Several distinct T helper (TH) subsets have been identified, based on the cytokines secreted. Recently, it has been demonstrated that these subsets can regulate the isotype of humoral responses. To investigate the possible differences in TH subsets between atopic donors which hav e elevated serum IgE and donors with normal serum IgE, we examined ser ies of human TH cell clones. A total of 31 and 22 CD4+ T cell clones f rom the atopic and non-atopic donors, respectively, were characterized for the ability to help for IgE synthesis in vitro. T cell clones gen erated with allergen AgE from the atopic donor were autoreactive and a ll induced IgE synthesis. Tetanus toxoid-specific (TT) and phytohaemag glutinin clones were generated from both donors. There was significant heterogeneity between the T cells isolated with different stimuli fro m the same atopic donor. Also, there was a significant difference in t he number of T cells generated from the atopic versus the non-atopic d onor which helped for IgE, although there was no significant differenc e between the total number of T cells able to help for immunoglobulin synthesis of other isotypes. Most importantly, there was a higher freq uency of clones able to support IgE synthesis between TT-specific T ce ll clones generated from the atopic versus the non-atopic donor. These results suggest that there are changes in subsets of TH cells specifi c for microbial antigens as well as allergens in atopics, which may ha ve important implications for the aetiology of atopic disease.