Impaired interleukin-1beta converting enzyme (ICE) activity in patients with pulmonary tuberculosis.

We measured the activity of IL-1beta converting enzyme (ICE) of monocytes from pulmonary tuberculosis (PTB) patients. Peripheral blood mononuclear cells (PBMCs) and serum were collected from PTB patients (n = 16) and healthy subjects (n = 6). Serum IL-18 levels were significantly higher in PTB patients (515.9 +/- 326.5 pg/ml) than in controls (108.7 +/- 65.2 pg/ml) (P < 0.01), but gradually decreased with tuberculosis therapy. ICE activity was significantly lower in TB patients (65.3 +/- 34.4 vs. 142.2 +/- 75.6 U/mg) (P < 0.05). Serum IL-18 levels inversely correlated with ICE activity (P < 0.05). Altered ICE activity may explain why there is reduced IFN-gamma production from PBMCs; however, serum IL-18 is probably not regulated by ICE in monocytes in TB patients.