Lymphocyte subpopulations, activation phenotypes, and spontaneous proliferation in tuberculous pleural effusions

The state of lymphocyte activation in tuberculous pleural effusions was studied. The proportion of cells at and beyond the G1 phase of the cell cycle displaying interleukin-2 receptor, transferrin receptor or gp 40/80 glycoprotein in avidin-biotin-peroxidase complex (ABC) staining was 6 +/- 2 percent, 8 +/- 3 percent, and 14 +/- 4 percent of all pleural fluid mononuclear cells, respectively. These findings imply that only a fraction of pleural fluid lymphocytes is activated in tuberculosis. The proportion of autoradiographically visualized 3H-thymidine incorporating blasts at the S phase of the cell cycle was 1.2 +/- 0.3 percent. This phenomenon further confirms the impression that, in spite of activation, most of the pleural fluid mononuclear cells are resting cells. The T4/T8 ratio in the functionally active blast cell population determined by a double labeling method combining ABC staining with autoradiography was similar to the total T4/T8 ratio (2.3 +/- 0.7 vs 2.7 +/- 0.8, p greater than 0.05) calculated for all pleural fluid mononuclear cells.