Monoester lipase activity in the red cells of patients with various blood disorders.

Membrane-bound monoester lipase (MEL) activity was measured by a radiochemical assay in intact red blood cells (RBC) from 77 patients with various blood disorders. MEL activity levels in their RBC were compared with levels in normal subjects. The increase in MEL activity was greatest in RBC of regenerative anaemias (N = 8) and blastic crisis of chronic granulocytic leukaemias (7) whereas a lesser, although significant, increase was found in acute non-lymphoblastic leukaemias (14). MEL activity was markedly decreased in RBC of erythroleukaemias (N = 5) and decreased to a lesser extent in acute lymphoblastic leukaemias (10) and in chronic myeloproliferative disorders other than chronic granulocytic leukaemias (8). MEL activity levels were roughly correlated with reticulocyte counts, but the relationship was not of predictive value in individual cases. Further exploration of the possible diagnostic or prognostic implications of these variations in enzyme levels seems warranted.