Immunotherapy reduces CD40L expression and modifies cytokine production in the CD4 cells of pollen allergy patients.

Allergen-specific immunotherapy (SIT) is the only intervention for IgE-mediated respiratory disorders.The aim of the study was to investigate the immunological modifications induced by SIT in patients allergic to olive and/or grass pollen by attempting to establish an association between these modifications and clinical improvements.We studied 29 patients who were allergic to olive and/or grass pollen. Patients were randomized to 2 groups: an active treatment group, comprising 19 allergic patients who received SIT, and a control group, formed by 10 allergic patients who received pharmacological treatment for their allergic symptoms but not immunotherapy. We used flow cytometry to analyze intracellular expression of the cytokines IL-4, IFN-gamma, IL-10, and TGF-beta1 in CD4+ T cells, as well as expression of Foxp3, the costimulatory CTLA-4 molecule, and the non-costimulatory CD40L molecule. To assess clinical changes, patients recorded their medication consumption, symptoms, and the limitation of daily activities using diary cards and quality of life questionnaires.Six months after initiation of SIT, we recorded a reduction in cell surface CD40L expression in the CD4+ T-cell population and a shift in the cytokine production profile (decrease in IL-4-producing CD4+ T cells and increase in IFN-gamma, IL-10, and TGF-beta1). These changes persisted after 12 months. Simultaneously, a clinical improvement was observed.SIT-induced clinical improvement is the result of immunological modifications such as a reduction in CD40L expression on CD4 cells and alteration in the cytokine production profile.