Carbohydrate metabolism in the leukocytes. I. The pathway of two- and three-carbon compounds in the rabbit polymorphonuclear leukocyte.

One of the unique characteristics of polymorphonuclear leukocytes from normal subjects is their high rate of aerobic and anaerobic glycolysis with accumulation of lactic acid (1,2). Intermediates and enzymes of the Embden-Meyerhof scheme have been isolated and identified (3-5) and Beck (6) has calculated the V,,, of a number of these enzymes. The results indicate the hexokinase to be the chief rate-limiting enzyme in human normal, chronic lymphocytic, and chronic myelocytic leukocyte homogenates. There are indications for an intact Krebs cycle in the human polymorphonuclear leukocyte (2, 7), even though the ratio of respiration to glycolysis has been found to be exceedingly low (8). In addition, the operation of the phosphogluconate oxidation pathway has been demonstrated by Coxon and Robinson (9) in white cells isolated from the peripheral blood of cats, rabbits, and dogs. Beck (10) in a further study has isolated and characterized certain enzymes of this oxidative pathway and has estimated about 3% of catabolized glucose to traverse this route in normal human leukocytes. The present study attempts to assess the role of the various carbohydrate pathways in the overall metabolism of the white blood cell. C14-labeled acetates, pyruvates, lactate, and glycerol have been incubated in vitro with rabbit polymorphonuclear leukocytes. The glycogen of the cells and the lactate of the medium were isolated, purified and the Cl4 distribution pattern determined by degradation. A preliminary report of this work has been presented (11).