Abstract
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 18 malignant tumors [in humans]. Esterase-positive lymphocytes were found in all tumors, the highest number in the peritumoral stroma. The reliability of the method was tested on lymph nodes, on fixed E-rosetting lymphocytes and on cryostat sections from peripheral blood lymphocytes.