Enhanced cytokine generation by peripheral blood mononuclear cells in allergic and asthma subjects

Background: Although preferential expression of the Th2 cytokines, IL-4 and IL-5, has been described in atopic asthma, the role of IFN-γ and IL-10 are less clear. Objective: To determine the cytokine pattern of T cell mitogen-induced peripheral blood mononuclear cells obtained from atopic asthmatic (AA) subjects. Methods: Peripheral blood mononuclear cells obtained from AA (n = 24), allergic rhinitis (AR) (n = 9), and normals (NL) (n = 9) were stimulated with phytohemagglutinin (PHA) and the generation of IL-4, IL-5, IFN-γ, IL-10, and GM-CSF was quantified using ELISA. Results: Compared with NL subjects, peripheral blood mononuclear cells from the atopic groups had increased generation of both IL-5 (AA, P = .001 and AR, P = .024) and IFN-γ (AA, P = .037 and AR, P = .048) and decreased generation of IL-10 (AA, P = .038 and AR, P = .036). The absolute levels of cytokines did not differ between the two atopic groups; however, the ratio of IL-5/IL-10 was significantly higher in AA (P < .05), but not in AR when compared with NL subjects. Conclusion: The concomitant increase in the generation of IL-5 and IFN-γ, with a decrease in IL-10 in the atopic groups suggests that in, at least a subset of these patients, there is potential expression of both Th2-and Th1-type cytokines. Furthermore, the increased IL-5 to IL-10 ratio could represent a key feature that distinguishes atopic asthmatic from non-asthmatic atopic subjects.