Cytochemical determination of granulocyte elastase and chymotrypsin in human myeloid cells and its application in acquired deficiency states and diagnosis of myeloid leukemia.

Two cytochemical methods for detection of granulocytic elastase and chymotrypsin employing alanine and phenylalanine naphthyl esters were developed. Specificity of reaction with the ester substrates was proven by chloromethyl ketone inhibitors. The results of both staining methods were almost identical with the staining for naphthol AS-D chloroacetate (Cl Ac-O Nap AS-D) esterase, since Cl Ac-O Nap AS-D also reacts with granulocyte elastase and chymotrypsin. Mature neutrophils and myeloid precursors except myeloblasts are stained with all three substrates in peripheral blood and bone marrow. Mast cells, however, only react with Cl Ac-O Nap AS-D and the chymotrypsin substrate and not with the elastase substrate. In acute myeloid leukemia the three esterases appear in parallel at a somewhat later stage of maturation than myeloperoxidase. In blood smears from 380 hospital patients no hereditary elastase or chymotrypsin deficiency could be demonstrated. Staining for elastase and chymotrypsin was also normal in hereditary myeloperoxidase deficiency and chronic granulomatous disease. On the other hand 6% of the hospital patients and about two-thirds of patients with acute myeloid leukemia showed a partial elastase deficiency in more than 25% of the peripheral neutrophils.