Candida albicans mannan- and protein-induced humoral, cellular and cytokine responses in atopic dermatitis patients

Background The cytokine observed most often in atopic dermatitis (AD) is IL -4, but a role for IL-5 and IFN-gamma in the late and delayed phase reactio ns has been suggested. In AD with head, neck and shoulder distribution, hyp ersensitivity to saprophytic yeasts is an important pathogenetic factor. Th e yeast allergens include both the mannan polysaccharides and the proteins. Mannans are major cross-reacting allergens likely to be involved in the pa thogenesis of AD. Objective To characterize the humoral, lymphoproliferative and cytokine (IL -2, 4, 5 and IFN-gamma) responses of peripheral blood mononuclear cells (PB MCs) induced by Candida albicans mannan and protein antigens in AD. Methods Fifteen AD patients and seven healthy controls were included. Ficol l-isolated PBMCs were stimulated by PHA and laboratory-generated mannan and protein extracts of C. albicans. Lymphocyte proliferation was measured and cytokine production was studied by ELISA. The antigen-specific IgG and IgE antibodies were analysed by ELISA and nitrocellulose RAST. Results In AD mannan (P < 0.005) and protein (P < 0.002), specific IgE leve ls were higher than in healthy controls. Both mannan and protein-specific l ymphoproliferations (both: P < 0.02) were higher in AD than in healthy cont rols. Mannan, but not protein, induced long lasting IL-2 and IL-4 productio ns from 24h lasting up to 66-96h and IL-5 and IFN-gamma productions with el evated levels at 66 and 96 h. The mannan-induced IL-2 (P = 0.015) and IFN-g amma (P < 0.005) were increased in AD as compared with healthy controls. Si gnificant correlations were seen between the protein-induced proliferation responses and both serum total IgE (r = 0.59, P < 0.01) and protein-specifi c IgE (r = 0.65, P < 0.005). The mannan-induced IL-2 responses correlated w ith the specific IgE (r = 0.62, P < 0.01) and proliferation (P = 0.51, P < 0.02) and S-IgE level (r = 0.71, P < 0.002). Mannan-induced IL-4 and IFN-ga mma productions also correlated (r = 0.43, P < 0.05). Conclusions C. albicans mannan induced elevated IL-2 and IFN-gamma response s in AD patients. The correlations of the cytokine responses with mannan-in duced ISE and proliferation responses suggest that C. albicans mannan induc ed TH1 type cytokine responses are involved in AD.