The effect of azathioprine was assessed in a long‐term study of 3 patients with refractory idiopathic thrombocytopenic purpura and 2 selected patients showing substantial evidence of systemic lupus erythematosus. A favorable clinical response to the immunosuppressive agent was observed in all patients, corresponding to the significant decrease of immunoglobulin levels. Since azathioprine failed to depress the cellular antibodies, the question remains, in view of the apparent clinical remissions, as to whether the clinical effects are actually based on suppression of the immunogenesis of these diseases.

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.

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In vitro induction of myelopoetic colonies from mouse bone marrow has been used for measurement of leucopoetic colony stimulating activity (CSA) isolated from large batches of human urine. After high flow dialysis in artificial kidneys and immediate adsorption to DEAE-Cellulose, followed by purification on Con A-Sepharose, treatment with insoluble Papain and gelfiltration on Sephadex G 100, enrichment of CSA was about 6,000-fold. An important step of the enrichment procedure was the separation from a CSA-inhibiting protein, probably combining with CSA. Specific activity was further increased by preparative polyacrylamide gel electrophoresis to 5.3 X 10(6) units per mg protein. The total enrichment exceeded 25,000-fold. The final purification product consisted of a group of closely related proteins with high specific activity. Antisera raised with one of the electrophoretic fractions suppressed bioactivity in each of the different purification steps including the final CSA fractions differing in electrophoretic mobility. The antisera furthermore inhibited CSA in human lung and monocyte conditioned media but had only very little effect on partially purified CSA from stimulated human lymphocytes as well as CSA derived from mouse lung conditioned medium.