| Abstract: | The existence of circulating factors in blood of possible importance for granulo-poiesis was investigated by examining the effect of sonicated serum on agar cultures of human haematopoietic cells. Ultrasound treatment of serum can activate enzymes normally bound to carrier proteins. In normal bone marrow cultures, growth was inhibited by sonicated serum when the cells were cultured in a single layer without exogenous colony-stimulating factor (CSF) included in the culture, while an enhancing effect with a 2–5 fold increase in the number of colonies was seen in feeder layer-stimulated cultures. Morphologically, in contrast to the normal change to eosinophils and monocytes-macrophages during the culture period, the cultures with sonicated serum added showed continuous growth of neutrophils and no increase of other cell types. Experiments using tritiated thymidine indicated that the enhancing effect of sonicated serum involved marrow cells which were more prone to thymidine S-phase kill. The effect of sonicated serum was further evaluated in cultures from patients with leukaemia. In AML in relapse, feeder-layer stimulated cultures of bone marrow cells were inhibited (11/14 cases) by sonicated serum, while reversion to the normal enhancing pattern was seen for patients in remission. |
