Seasonal comparison of cytokine profiles in atopic asthmatics and atopic non-asthmatics

Previous studies have suggested that peripheral blood T cell cytokine release may reflect the situation in the bronchial mucosa in atopic asthmatics. We have therefore examined spontaneous, rye grass pollen-stimulated, and PHA-stimulated secretion of IL-2, IL-4, IL-5, and IFN-gamma in cultures of peripheral blood mononuclear cells (PBMC) from atopic asthmatic, atopic non-asthmatic and normal controls in and out of the rye grass pollen season. Compared to normal controls, both atopic groups showed higher IL-2 and IL-5 production (p < 0.01 and p < 0.05) and higher percentages of CD4 cells expressing CD25 and HLA-DR (p < 0.05) in response to rye grass pollen, elevated IL-4 production in response to PHA (p < 0.01), and a non-significant trend towards lower IFN-gamma production. However, the capacity of PBMC from atopic asthmatics to produce IL-5 was greater than that for atopic non-asthmatics (p < 0.05). Furthermore, seasonal changes in symptom score, FEV1 % predicted, and PD20 methacholine correlated with seasonal elevated production of IL-5 by PBMC in the asthmatic group (r = 0.862, -0.679, and -0.620; p < 0.01, 0.02, and 0.05, respectively). Our results suggest that elevated production of IL-2 and IL-4 and higher percentages of activated CD4 T cells are associated with atopy per se, but elevated production of IL-5 also relates to the clinical expression of atopic asthma.