[Detection of T lymphocytes with acid alpha-naphthyl acetate esterase. Specificity and use in pleural effusions]

A modified technique for demonstration of acid alpha-naphthylacetate esterase was examined with regard to specificity and application on human T-lymphocytes in peripheral blood and pleural fluids of different genesis. T-lymphocytes of healthy donors showed only in 60% positive findings of acid alpha-naphthylacetate esterase. Positive reactions appear as dot-like reaction products in cytoplasm of lymphocytes. The application of this method on pleural fluids is possible, without technical problems. We found differences in the percentage of positive-reacting lymphocytes in pleural fluids between tuberculosis (= 78% T-cell esterase positive lymphocytes) and tumors (= 65% T-cell esterase positive lymphocytes). Mesotheliomas exhibit very low positive findings (= 32% T-cell esterase positive lymphocytes) in contrast to carcinomas. In this way, acid alpha-naphthylacetate esterase may be helpful in some cases as a diagnostic aid.