Objective:To investigate the effect of anti-CD3 plus anti-CD28 antibody co-stimulation on the release of interleukin-17 A (IL-17A) in human peripheral blood mononuclear cells (PBMCs). And the effect of triptolide on IL-17A release was also studied. Methods:PBMCs were stimulated with anti-CD3 monoclonal antibody (10 μg/ml) and anti-CD28 monoclonal antibody (10 μg/ml). ELISA was applied to measure the concentration of IL-17A in the supernatant of the cell culture. Results:IL-17A was released in time-dependant manner by PBMCs due to anti-CD3 plus anti-CD28 co-stimulation,however the release could be inhibited by triptolide at the concentration of either 100 nmol/L or 500 nmol/L. Conclusion:IL-17A produced by PBMCs might play an important role in the mechanism of asthma. Triptolide might inhibit the Th2 type allergic inflammation in asthma through reducing the release of the IL-17A.