T lymphocytes in malignant, non-lymphoid human tumours detected by esterase technique.

The alpha-naphthyl acetate esterase (ANAE) method, leading to distinct brownish-red dots in the cytoplasm of T lymphocytes, was used to identify these cells in cryostat sections from eighteen malignant tumours. Esterase-positive lymphocytes were found in all tumours, the highest number in the peritumoural stroma. The reliability of the method was tested on lymph nodes, on fixed E-rosetting lymphocytes and on cryostat sections from peripheral blood lymphocytes.