CD8+ T cell activation and differentiation in allergic asthma and the impact of cytomegalovirus serological status

Abstract

Summary Allergic asthma is a chronic inflammatory T helper 2 (Th2)-associated disease. There is evidence that the atopic milieu affects the development of CD8+ T cells in patients. We therefore analysed activation and differentiation states of CD8+ T cells in asymptomatic patients regarding the cytomegalovirus serological status. Memory CD8+ T cells (CCR5highCD3+CD8+), memory/effector cells (CD27+CD28–CD3+CD8+), effector cells (CD27–CD28–CD3+CD8+) and activated CD8+ T cells (CD11b+CD3+CD8+) were identified by flow cytometry in peripheral blood of 19 (seven cytomegalovirus (CMV)+/12 CMV–) patients with allergic asthma (AA) and 21 (seven CMV+/14 CMV–) healthy controls (HC). Effector and activated CD8+ T cells were significantly elevated in CMV+ HC compared to CMV– HC. There was a non-significant trend for reduced percentages of effector CD8+ T cells in CMV+ AA (median: 10·4%, range: 4·4–33·8%) compared to CMV+ HC (median: 23·1%, range: 10·7–54·1%; P = 0·128) and in CMV– AA (median: 4·1%, range: 0·6–13·4%) compared to CMV– HC (median: 5·7%, range: 0·2–17·0%; P = 0·085). Activated CD8+ T cells were reduced significantly in CMV+ AA (median: 17·0%, range: 6·0–29·4%) compared to CMV+ HC (median: 40·4%, range: 18·9–67·0%; P = 0·004) and showed a non-significant trend in CMV– AA (median: 15·0%, range: 2·9–24·0%) compared to CMV– HC (median: 20·2%, range: 5·8–71·0%; P = 0·060). Activated CD8+ T cells are significantly reduced in CMV+ patients with allergic asthma. Furthermore, a trend for an impaired terminal CD8+ T cell differentiation is observed in CMV+ and CMV– patients with asthma.