Cell membrane enzymes: L-gamma-glutamyl transpeptidase, leucine aminopeptidase, maltase and trehalase in normal and leukaemic lymphocytes.

Several cell-membrane enzymes, which serve functions in amino acid and sugar transport, were measured in peripheral blood lymphocytes from chronic B and T lymphocytic disorders, blast cells in acute leukaemias, and in normal lymphocytes from cord blood, peripheral blood of adults, tonsils and bone-marrow plasma cells in myelomatosis. The specific activities of L-gamma-glutamyl transpeptidase, maltase and trehalase were low, as compared with those measured in normal blood lymphocytes, in the acute leukaemias and in the chronic B-cell disorders. In myelomatosis and in the chronic T-cell disorders, the specific activity of these three enzymes was in the normal range or above normal. The specific activity of leucine aminopeptidase was low in all the chronic B-cell disorders and in some of the lymphoblastic leukaemias. It was elevated in Sézary syndrome cells but low in T-chronic lymphocytic leukaemia. All four enzymes were lower than normal in cord blood lymphocytes and higher than normal in tonsils. These findings are discussed in relation to the patterns of lymphoid cell differentiation and maturation in normal tissues and in leukaemic states.