Immunolgic study of pleural fluid in patients with tuberculous effusion

Abstract

Pleural fluid mononuclear cells (PFMC) and peripheral blood mononuclear cells (PBMC) from 10 patients with tuberculous effusion were analysed quantitatively for T-lymphocyte and T-lymphocyte subsets as well as functionally for purified protein derivative (PPD)-induced lymphocyte transformation and inhibition of leukocyte migration. The results were compared with the PFMC and PBMC obtained from 15 patients with carcinomatous effusion. It was found that the majority of the leukocytes in the tuberculous and malignant pleural effusions were T-cells and T helper/inducer cells but quantitative analyses of T cells and T cell subsets in PFMC could not differentiate tuberculous from malignant effusions. And, when compared to the peripheral blood, the T helper/suppressor rations in PFMC of both tuberculous and nontuberculous effusions were significantly higher than PBMC (p<0.001) due to the increase of helper and decrease of the suppressor T cells (p<0.001 and <0.005 respectively). A positive specific (PPD-stimulated) lymphocyte transformation test was found only in the tuberculous group whether PBMC or malignant PFMC were used. Similarly, PPD-stimulated inhibition of leukocyte migration was also found only in the PFMC and PBMC of tuberculous patients. Such a good correlation indicates that both the PPD-stimulated lymphocyte transformation test and the PPD-stimulated leukocyte migration inhibition test (LIF) may add to the diagnostic value of the conventional bacteriological, pathological and clinical diagnosis of tuberculous effusion (p<0.005). A positive tuberculin test alone could not be used to differentiate tuberculous fromnontuberculous pleural effusions. It was found to statistically correlate well with PPD-stimulated proliferative response of PBMC (r=0.6). Free leukocyte migration inhibition-like factor (LIF) could be demonstrated in the pleural fluids of both tuberculous and malignant pleural effusions which might reflect the in situ interactions between the tuberculous and carcinomatous antigens with the diseased pleural tissues. Therefore, although it is simpler, free LIF-like activity in pleural effusion cannot be used to differentiate tuberculous from malignant pleural effusions.