Objective: To investigate the effect of mitogen Phorbol 12-myristate 13-Acetate (PMA) on CD3, CD4 and CD8 expression of human T-lymphocytes.
Methods: Peripheral blood mononuclear cells from 37 blood samples stimulated in vitro with PMA at different concentrations (2,5,10,20 and 50 ng/ml for 4 hours) and time (10 ng/ml for 2,4 and 6 hours) were analyzed by 4-color flow cytometry (FCM).
Results: Under different PMA stimulation protocols,significant CD4 down-regulation was observed,which was negatively correlated with intracellular cytokine secretion (r= 0.601,P<.001), except for PMA stimulation at 10 ng/ml for 2-hours which showed no significant intracellular cytokine secretion. The expressions of CD3 and CD8 molecules after PMA activation were not significantly affected as compared with pre-activation. Among CD3 positive T lymphocytes, CD4/CD8 double-negative cells only account for 5.52%.
Conclusion: PMA has a significant down-regulation effect on CD4 molecules of Th cells, without altering the CD3 and CD8 expression. For quantitative analysis of Th1/Th2 variation, indirect method such as CD3(+)CD8( ) T cells can be used to define CD4(+) Th cells stimulated by PMA in the future.