T-lymphocyte subsets in pleural fluids: discrimination according to traditional and monoclonal antibody-defined markers.

T-lymphocyte subpopulations in pleural fluid and in peripheral blood from 17 patients admitted for pleural effusion were identified by E-rosette formation and delineated by monoclonal antibodies OKT3 (peripheral T-cells), OKT4 (helper/inducer cells), and OKT8 (suppressor/cytotoxic cells). We studied 13 patients with specified pleural diseases (tuberculosis, malignancies, connective tissue diseases, congestive heart failure) and 4 patients with non-specified pleural diseases. Our findings showed that the percentage of T-cells increases in pleural fluid versus peripheral blood whatever the diagnosis is, and that these T-cells are predominantly helper/inducer cells. Moreover, a recently described T-lymphocyte subpopulation, which expresses neither T3 nor other monoclonal antibody-defined markers, seems to be concentrated in the pleural fluid, especially in tuberculosis and malignant effusions. Although T-lymphocyte delineation seems to fail to aid in etiological diagnosis of pleurisy, such determinations could provide informations about local pathogenic mechanisms.