Abstract: Objective To explore the clinical expression and significance of CD3+ T cells, CD3+CD16+CD56+ N KT cells and CD3-CD16+CD56+ N K cells in pulmonary TB patients. Methods Percentages of T cells, N KT and NK cells in peripheral whole blood samples from 123 pulmonary TB patients (73 first-treated pulmonary TB and 50 retreated pulmonary TB) and 83 healthy controls (43 positive PPD test and 40 negative PPD test) were analyzed by flowcytometry.  Results Percentage of NKT cells in first-treated and retreated pulmonary TB patients significantly increased than that in healthy controls (P<0.01), but percentages of T and NK cells had no significant difference between first-treated pulmonary TB patients and healthy controls(P>0.05). There was also a significant difference in the percentage of T cells according to severity of disease（P<0.01）,while no significant difference in the percentages of NKT and NK cells could be found among these groups (P>0.05). Percentage of T cells in retreated pulmonary TB patients was significantly higher as compared with first-treated pulmonary TB patients (P<0.01), but those of NKT and NK cells had no significant difference (P>0.05).  Conclusion s T and NKT cells play an important role in cellular immunity against TB. To monitor the percentage of T cells in peripheral blood for pulmonary TB patients is helpful in finding recurrent tuberculosis and predicting prognosis. NKT cells in peripheral blood increase only in active TB patients. It can be used as one of the assistant non-invasive indicators for active pulmonary TB.

Key words: tuberculosis, pulmonary/ blood, T-lymphocytes, killer cells, natural