Peripheral blood CD4+ and CD8+ T cell type 1 and type 2 cytokine production in atopic asthmatic and normal subjects

Background Increased production of IL-4 and IL-5 and decreased production of IFN-gamma by CD4(+) T cells has been implicated in asthma pathogenesis. However, CD8(+) T cells also produce type I and type 2 cytokines and the relative roles of CD4(+) and CD8(+) T cell cytokine production in asthma have not been previously studied. Objective To determine the production of the type I and type 2 cytokines by CD4(+) and CD8(+) T cell subsets in asthmatic and normal subjects. Methods Intracellular cytokine staining for IL-4, -5, -10, -13 and IFN-gamma was analysed in peripheral blood CD4(+) and CD8(+) T cells from 24 atopic asthmatic and 20 normal subjects. Results Both subsets of T cells produced all cytokines studied and there were no significant differences between CD4(+). and CD8(+) T cells in their capacity to produce either type I or type 2 cytokines. There were significantly increased frequencies of IFN-gamma-positive CD4(+) (13.1 +/- 2.4%, vs. 7.3 +/- 1.4%) and CD8(+) (20.0 +/- 2.9%, vs. 9.6 +/- 2.1%) T cells in asthmatic subjects compared with normal subjects (P<0.05), but not in frequencies of CD4(+) or CD8(+) T cells staining positively for IL-4, -5, -10 or -13. Conclusion The frequencies of peripheral blood CD8+ T cells producing type I and type 2 cytokines are comparable with the frequencies of CD4(+) T cells. There was an increased frequency of IFN-gamma producing CD4(+) and CD8(+) T cells in asthmatic compared with normal subjects. Further studies investigating T cells derived from the airways and investigating various stages within the disease process are required to further elucidate the importance of type 2 and type 1 T cell cytokine production in the pathogenesis of human allergic disease.