Altered expressions of helper T cell (Th)1, Th2, and Th17 cytokines in CD8(+) and γδ T cells in patients with allergic asthma

Abstract

Background: T cells play an important role in orchestrating allergic asthma by producing various cytokines; however, little information is available on the phenotype of cytokine-producing T cells, especially CD8(+) T and γδ T cells in humans.

Objective: The aim of this study was to investigate the role of cytokine expressions from circulating CD4(+), CD8(+), and γδ T cells in patients with allergic asthma.

Methods: Peripheral blood mononuclear cells were isolated from patients with allergic asthma (n = 29) and healthy controls (n = 12). The percentage of helper T cell (Th)1-, Th2-, and Th17-type cytokines interferon-γ (IFN-γ), interleukin (IL)-4, and IL-17, respectively, of CD4(+), CD8(+), and γδ T cells was analyzed by flow cytometry.

Results: The percentages of IL-4(+) and IL-17(+) CD4(+) T cells increased, whereas IFN-γ(+) CD4(+) T cells decreased in patients with allergic asthma compared with healthy controls. The frequency of IL-17(+) CD4(+) T cells tended to increase with the severity of allergic asthma. Higher frequency of IL-4-producing and lower frequency of IFN-γ-producing CD8(+) and γδ T cells were found in patients with allergic asthma compared with healthy controls. The IFN-γ(+)/IL-17(+) ratio among CD4(+), CD8(+), and γδ T cells was significantly decreased in patients with allergic asthma compared with healthy controls.

Conclusion: CD8(+) and γδ T cells might be involved in the pathogenesis of allergic asthma through the release of Th1-, Th2-, and Th17-type cytokines.