Abstract
Pleural fluids obtained from 17 patients- 7 with malignant pleurisy, 6 with infectious pleurisy, 4 with transudative pleurisy were analyzed for total hemolytic complement titers (CH 50), levels of six complement (C) components (C1q, C1s, C4, C3, factor B and C5), conversion products of C3, immune complexes (IC) and anti-complementary activities. The mean levels of each CH 50, C4 and C3 in the malignant group were significantly reduced compared with those in the infectious group (P<0.001, P<0.01, P<0.1 respectively) and also those in the transudative group (P<0.01, P<0.1, P<0.05 respectively). The mean level of C1q in the malignant group was lower than that in the infectious group (P<0.001). The mean level of conversion products of C3 in the malignant group (P<0.05) as well as that in the infectious group (P<0.1) increased compared with the transudative group. Neither IC nor anti-complementary activities were found in the malignant group. The above results suggested that the binding of tumor-specific antibodies to tumor cells might activate classical C pathway mainly and cause C depletion in malignant pleural effusions.
