Summary
The expression of CD8 +CD25 +FoxP3 + regulatory T cells (CD8 +Tregs) in the peripheral blood of patients with stable chronic obstructive pulmonary disease (COPD), and the effect of muscarinic cholinergic receptor antagonist tiotropium bromide on the expression of CD8 +Tregs were investigated. Twenty-three patients with moderate to severe stable COPD were enrolled in this study. All patients inhaled tiotropium bromide (18 μg daily) for 3 months. Before and after inhalation of tiotropium bromide, peripheral blood samples were collected from the patients, and T cells were labeled by three-color labeled monoclonal antibodies. Flow cytometry was used to detect the quantity and percentage of CD8 +T cells, CD8 +CD25 +T cells, CD8 +Tregs, CD4 +T cells, CD4 +CD25 +T cells and CD4 +CD25 +FoxP3 + regulatory T cells (CD4 +Tregs) respectively. The percentage of CD4 +T cells was increased from (27.82±2.18)% to (35.53±1.3)% (t=3.20, P=0.004) in the peripheral blood of patients with stable COPD after inhalation of tiotropium bromide for 3 months, that of CD4 +CD25 +T cells was decreased from (10.03 ±1.42)% to (4.21 ±0.65)% (t=3.78, P=0.001), and that of CD8 +Tregs was increased from (8.41 ±1.68)% to (21.34 ±4.20)% (t=2.72, P=0.013). At baseline, CD8 +T cells, CD8 +CD25 +T cells and CD4 +Tregs were detectable in the peripheral blood, but no significant changes were observed after treatment. Linear correlation analysis revealed that the difference before and after treatment in CD4 +T cells and CD4 +CD25 +T cells was negatively correlated with the ratio of change in CD8 +Tregs before and after treatment (r=−0.61, P=0.013; r=-0.72, P=0.001 respectively). In the peripheral blood of patients with stable COPD, there was the expression of CD8 +Tregs and CD4 +Tregs. Muscarinic receptor antagonist, tiotropium bromide, can promote the amplification of CD4 +T cells, inhibit the expression of CD25 +T cells, and enhance the expression of CD8 +Tregs. CD8 +Tregs and CD4 +Tregs can be used as new indicators to understand the immune status of patients. They are helpful in judging the treatment efficacy and disease immunophenotype.