ObjectiveTo investigate the expression of programmed cell death-1 (PD-1), interferon-γ (IFN-γ), interleukin-4 (IL-4) and T help cells (Th) in peripheral blood of patients with asthma.MethodsForty-one asthma patients were divided into an acute group (20 cases) and a chronic group (21 cases) according to the disease state of asthma. Another 18 healthy subjects were recruited as a control group. Peripheral blood samples were collected from all the subjects at admission or inclusion. The concentrations of PD-1, IFN-γ and IL-4 were detected by enzyme-linked immunoassay method. The expressions of Th1 and Th2 were detected by flow cytometry method.ResultsThe PD-1 and IFN-γ concentrations, Th1 proportion and Th1/Th2 ratio in the two asthma groups were reduced compared with the healthy control group, and were significantly lower in the acute group compared with the chronic group (all P<0.05). The IL-4 level and Th2 proportion in the two asthma groups were increased compared with the healthy control group, and were significantly higher in the acute group than the chronic group (allP<0.05). In the acute group, the PD-1 level was positively correlated with IFN-γ and Th1 level (r values were 0.678 and 0.712, respectively), and negatively correlated with IL-4 and Th2 (r values were –0.745 and –0.700, respectively).ConclusionThe concentration of PD-1 in patients with asthma is reduced especially in acute asthma, and shows close correlation with conventional index of asthma.