Yale Rabinowitz

Effects of phytohemagglutinin on rat and normal and leukemic human blood cells.

Summary Suspensions of normal human blood cells were incubated at 37°C with phytohemagglutinin (PHA) in slide chambers. In 2 to 4 days, the reagent stimulated the formation of large blast-like cells (PHA-cells) which could be readily differentiated from macrophages. PHA-cells developed in purified suspensions of lymphocytes and many intermediate cells were seen between PHA-cells and lymphocytes. PHA-cells did not develop in blood cell suspensions of some patients with chronic lymphocytic leukemia nor in suspensions of rat blood cells. The findings suggest that PHA-cells were derived from normal human lymphocytes and should be differentiated from macrophages.

Genetic control of lactate dehydrogenase and malate dehydrogenase isozymes in cultures of lymphocytes and granulocytes: Effect of addition of phytohemagglutinin, actinomycin D or puromycin

1. 1. The effect of the addition of phytohemagglutinin to cultures of purified lymphocytes and granulocytes upon the isozymes of lactate dehydrogenase (l-lactate:NAD oxidoreductase, EC 1.1.1.27) and malate dehydrogenase (l-malate:NAD oxidoreductase, EC 1.1.1.37) was studied. 2. 2. Increase in the proportion of muscle-type (M-type) lactate dehydrogenase was demonstrable with acrylamide-gel disc electrophoresis in 4 h, while a significant increase (P < 0.001) occurred within 24 h. Actinomycin D or puromycin prevented this change. Granulocytes, which had a high proportion of M-type lactate dehydrogenase initially, showed no alteration in the isozyme pattern in cultures with or without phytohemagglutinin. 3. 3. Two malate dehydrogenase isozyme bands were found in lymphocytes and granulocytes. The slow-moving Band 2 represented 44.8% of the total malate dehydrogenase in lymphocytes and only 13.4% in granulocytes. In cultures, with or without phytohemagglutinin, little change was seen in lymphocytes. Granulocytes, however, showed a marked increase in Band 2 (P < 0.001) in 24 h, but this occurred with or without the addition of phytohemagglutinin. Actinomycin D or puromycin blocked this change. 4. 4. The results indicate that in lymphocytes phytohemagglutinin acts at the two genetic loci controlling synthesis of muscle- and heart-type (M- and H-)lactate dehydrogenase polypeptide subunits. The synthesis of the two isozymes of malate dehydrogenase also may be under the control of separate genes which in granulocytes are influenced by conditions of cell culture, rather than by phytohemagglutinin.

Studies of Cell Source of Macrophages from Human Blood in Slide Chambers.

Summary In slide chambers the number of macrophages formed closely paralleled the number of monocytes present in the initial suspension. When most monocytes were removed by glass beads very few macrophages formed. When lymphocytes were removed by irradiation the number of macrophages formed corresponded to the number of monocytes at the start. Intermediate stages between lymphocytes and macrophages were never observed, whereas cells intermediate between monocyte and macrophage were regularly seen.