OBJECTIVETo investigate the phenotype, frequency and function of CD4+ T cell subsets and the relevant cytokines, as well as the relationship between these cells and appearance of pneumonia of novel (H1N1) influenza A patients.

METHODS68 healthy people, 53 confirmed novel A(H1N1) influenza patients without pneumonia and 16 confirmed severe novel A (H1N1) influenza patients with pneumonia were enrolled in this study. Viral load in nasopharyngeal swabs specimens was measured by real time PCR assay. The phenotype and percentage of CD4+ T cell subsets including Th1, Th2, Th17, and Treg cells were measured by Flow cytometry analysis. The relevant cytokines in plasma including TGF-beta, IL-6 and IFN-gamma were measured by ELISA. Data was analyzed by one way ANOVA.

RESULTSIt was found that peak viral load and viral shedding period of severe patients with pneumonia was significantly increased compared with mild patients without pneumonia (P < 0.05). The percentage of Th17 cells of severe patients with pneumonia was significantly diminished compared to that of healthy subjects and mild patients without pneumonia (P < 0.05). However, Th1, Th2, Treg cells frequencies had no significant differences (P > 0.05) among these three groups. The level of TGF-beta in plasma for the severe patients with pneumonia was also significantly decreased compared to that of healthy subject and mild patients without pneumonia (P < 0.05). The viral shedding period inversely correlated with the frequency of Th17 cells (r = - 0.38, P < 0.05).

CONCLUSIONH1N1 influenza A virus can inhibit Th17 cells to differentiate, particularly more extent in patients with pneumonia. Impaired Th17 cells may correlate with viral clearance and pneumonia of novel H1N1 influenza A patients.