Factors affecting RNA synthesis in rat bone-marrow cells

ABSTRACT

Neutrophils which are the first type of cells observed in the course of an inflammatory response to injury, are severely depleted in bone-marrow cells of animals after injection of antigens and insoluble thrombin, both of which provoke an inflammatory response. Increased RNA synthesis in neutrophils on phagocytosis of solid particles has also been reported. Since inhibitors of RNA synthesis in vivo can prevent the mobilisation of lymphocytes but not of neutrophils to the damaged area, and the arrival of lymphocytes is dependent on prior presence of neutrophils, it is possible that RNA synthesized in neutrophils controls the mobilisation of lymhocytes in the inflammatory response. Consistent with this hypothesis is the finding that neutrophils disintegrate after phagocytosis thus RNA so released could be taken up by lymphocytes. A study was therefore conducted on the effect of various chemotactic and phagocytosis - promoting factors on H3-uridine incorporation into RNA by rat bone-marrow cells. These cells have a high concentration of neutrophils. Chemotactic factors, anti-genantibody complexes, fibrin and fibrinogen had little effect on H3-uridine incorporation into RNA. A delipidized bovine plasma fraction, which has fibrinolytic activity, stimulated the incorporation of H3-uridine into these cells. A study of phagocytosis-promoting globulin led to the purification of a post-heparin lipoprotein lipase enzyme which stimulated RNA synthesis in bone marrow cells and also in peritoneal neutrophils. The results suggest that this enzyme increases RNA synthesis in neutrophils by affecting the plasma membrane. This could be an important reaction in the control of the inflammatory response(AU)