Cytochemical study of thymocytes and T lymphocytes

Fetal and postnatal thymocytes and circulating T lymphocytes were evaluated for six cytochemical reactions. Acid phosphatase activity was present in a high percentage of cells in all threee groups. Beta-glucoronidase and alpha-naphthyl acetate acid esterase were negative in the most immature fetal thymocytes, but become increasingly positive with T-cell maturation. Only the circulating lymphocytes presented a high percentage of N-acetyl beta glucosaminidase, alpha-naphthyl acetate esterase and alpha-naphthyl butyrate esterase positive cells. This study discusses the presence of these enzymes as proportional to different stages in T-cell maturation, and also of certain cytochemical phenotypes characteristic of these stages.