Does IL-4 play a role in the expansion of v beta 8a T cell receptor-bearing cells?

Background: Peripheral blood mononuclear cells (PBMC) of subjects allergic to the insect-derived allergen Chi t 1-9 are characterized by an allergen-i nduced pronounced proliferation and increased expression of activation mark ers (CD25, HLA-DR, CD23). T cell lines showed an elevated percentage of V b eta 8a-positive cells following stimulation by Chi t 1-9. Objective: The ai m of the present study was to investigate whether V beta 8a dominance plays an important role in PBMC short-term cultures (24 h) as well. The role of exogenous added cytokines, especially IL-4, has been determined. Methods: T he T cell receptor repertoire was measured with 16 monoclonal antibodies to epitopes on the variable region of the p chain by flow cytometry. Patients allergic to Chi t 1-9 were compared to nonallergic subjects as well as to subjects with other occupational allergies. In addition, cytokines were det ermined intracellulary by flow cytometry. Studies were performed with PBMC cultured for 24 h. Results: After cultivation for 24 h without or with diff erent stimuli (cytokines, allergen, phytohaemagglutinin), changes in the T cell receptor profile and the cytokine profile were measurable compared to the baseline value (without cultivation). Stimulation with IL-4 revealed in creased percentages of V beta 8a-expressing cells in Chi t 1-9-sensitized p atients. This IL-4-induced V beta 8a increase did not occur in PB MC fro m the two control subject groups (non-allergic and allergic to other allergen s than Chi t 1-9). Conclusion: In conclusion, the dominance of certain T ce ll receptor types seems to arise due to the exposure to specific allergens and cytokine production. Some T cell receptors are often affected, for exam ple V beta 8a, whereas others only show minor variations. V beta 8a express ion obviously plays an important role in Chi t 1-9 allergy. Copyright (C) 2 001 S.Karger AG, Basel