In vivo platelet and T-lymphocyte activities during pulmonary tuberculosis

Platelets have been suggested to play a role in the inflammatory response, including defence against bacteria. The aims of this study were to determin e in vivo platelet activity during the clinical course of pulmonary tubercu losis and to investigate whether or not there is a correlation between the magnitude of platelet activation and the extent of the pulmonary disease. T -lymphocyte activity was also analysed in the patients. Platelet factor-4 ( PF4) and soluble interleukin-2 receptor-alpha (sIL-2R alpha) concentrations were used as markers of platelet and T-lymphocyte activation, respectively . Twenty-five patients with pulmonary tuberculosis were studied. Fifteen heal thy subjects served as a control group. The levels of both sIL-2Ra (3,000+/-1948 pg.mL(-1)) and PF4 (103.1+/-6.7 IU .mL(-1)) were significantly higher in the patients with tuberculosis than i n the control group (984+/-360 pg.mL(-1) and 78.2+/-23.9 IU.mL(-1), respect ively) (Mann-Whitney U-test, p<0.001 for both comparisons). The plasma PF4 levels were found to be well correlated with the extent of pulmonary lesion s on chest radiography (the Spearman's bivariate correlation analysis, r=0. 65, p<0.001), However, sIL-2R alpha concentrations did not correlate with t he extent of disease. In conclusion, it has been suggested that platelet and T-lymphocyte activat ion occurs during pulmonary tuberculosis. The good correlation between plat elet activation and the extent of pulmonary tuberculosis might be ascribed to a pathophysiological role of platelets in pulmonary tuberculosis.