Our study was undertaken to investigate the role of tumor necrosis fac
tor-alpha (TNF-alpha) at the site of disease activity in tuberculous p
leuritis (TP). Concentrations of TNF-a were measured directly by radio
immunoassay (RIA) in the pleural fluid (PF) and plasma (P) of patients
with TP (n = 14), malignant effusions (n = 18) and transudates (It =
7). Among these three groups mean plasma levels of TNF-alpha were not
statistically significant (P > 0.05), but in the TP group mean levels
of TNF-alpha in PF were significantly higher than in the cancer and tr
ansudate groups (P < 0.001), and there was no significant difference b
etween the cancer and transudate groups (P > 0.05). These results may
indicate a local synthesis of TNF-alpha by cells within the pleural ca
vity in this disease.