Ultrastructural patterns of the alpha-naphthyl butyrate esterase activity in normal and leukaemic peripheral blood leucocytes.

The activity of alpha-naphthyl butyrate esterase was investigated at the ultrastructural level in normal human peripheral blood and in a few cases of hairy cell leukaemia, B-chronic lymphocytic leukaemia and acute monocytic leukaemia. A membrane reactivity was detected in most normal monocytes and lymphocytes. The activity in monocytes was very strong and was inhibited by NaF. It was NaF-resistant and less intense in lymphocytes. The reaction product was localized in the cytoplasm only in a small percentage of lymphocytes. In lymphocytes and monoblasts from pathological samples the pattern of reactivity was similar to that found in their normal counterparts, except for a lower intensity. The hairy cells showed a discrete distribution of the NaF-resistant reaction product on their cell surface. The different patterns of enzyme distribution are discussed critically.