Deficiency of factor B of the complement system in sickle cell anaemia

Factors B and D as well as the total activity of the alternative pathway of complement activation were measured using a functional assay in sera from 29 patients with sickle cell anaemia and 18 normal controls. Total alternative pathway activity was reduced in the patients compared with controls. In patients with abnormally low total alternative pathway activity factor D levels were normal, whereas factor B levels were significantly depresed to a mean level of about half of normal. Regression analysis in patients also showed a singnificant relation between total alternative pathway activity and factor B levels. A deficiency of factor B is the likely cause of the defect in the complement system in patients with sickle cell anaemia. Such a defect may contribute to the excessive proneness of such patients to severe infection.(AU)

Factors affecting RNA synthesis in rat bone-marrow cells

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)