Cytochemical analysis of acid hydrolases expression during phorbol diester (TPA)-driven differentiation of B-chronic lymphocytic leukaemia cells in vitro.

Four acid hydrolases, acid phosphatase (AP), alpha-naphthyl acetate acid esterase (ANAE), beta-glucuronidase (BG) and N-acetyl-beta-glucosaminidase (NABG) were determined cytochemically in B-chronic lymphocytic leukaemia (B-CLL) cells exposed in vitro to the tumor promoter 12-0-tetradecanoyl phorbol 13 acetate (TPA). TPA, which has been previously shown to induce B-CLL cells to mature towards plasmacytoid cells, results in the progressive expression of the enzymes tested in the cytoplasm of malignant cells, in particular AP and ANAE. Furthermore, the sensitivity to inhibitors and the pattern of reactivity of ANAE provide evidence for an enzyme subtype normally restricted to plasma cells. Thus, acid hydrolases--some of which showing plasma cell type of activity--are expressed during B-CLL cells differentiation induced in vitro. These results confirm the value of cytochemistry in subtyping B-cell malignancies.