Elevated Serum Levels of CCL17 Correlate with Increased Peripheral Blood Platelet Count in Patients with Active Tuberculosis in China

The serum levels of Th2 markers, including CCL17 (thymus and activation-regulated chemokine [TARC]), CCL22 (macrophage-derived chemokine [MDC]), and soluble CD30, were measured in 101 HIV-negative tuberculosis patients, 103 healthy community controls, and 18 tuberculosis patients in recovery. The levels of CCL17/TARC (249.8 +/- 19.91 versus 143.9 +/- 10.54, P < 0.0001) and sCD30 (7.78 +/- 0.44 versus 4.93 +/- 0.23, P < 0.0001) were significantly higher in patients with active tuberculosis than in controls; however, the CCL22/MDC serum level had no statistical difference between the groups (579.9 +/- 16.42 versus 556.5 +/- 15.29, P = 0.298). The counts of platelet and eosinophil in the peripheral blood of patients with active tuberculosis are significantly increased as well (289.4 +/- 8.14 versus 248.3 +/- 5.34 [P < 0.0001] and 165.1 +/- 14.33 versus 102.5 +/- 10.72 [P = 0.0005], respectively), and the platelet counts were positively correlated with serum TARC levels (Pearson r = 0.456, P < 0.0001), which indicates a new source of Th2 bias showing in active TB patients.