Putative role for lithium in human hematopoiesis.

Ingestion of lithium salts increases production of neutrophil granulocytes from the bone marrow in human subjects when the concentration of the ion in blood is within the range 5 to 10 X 10(-4) mol/L. Results of preliminary dose-response experiments appeared to indicate that nanomolar levels of lithium stimulated clonal proliferation of granulocyte precursors from normal bone marrow in vitro, suggesting the possibility that this element may contribute to the physiologic regulation of blood cell formation in humans. The present studies confirm that the influence of lithium on hematopoiesis is evident in vitro at concentrations equivalent to that demonstrable in normal blood (2 to 4 X 10(-7) mol/L). Furthermore, such effects are not cell lineage specific, being observed also in clonogenic cultures of erythroid and eosinophil granulocyte progenitor cells, and the phenomenon attributed to lithium is a property shared with rubidium and cesium salts. These findings point to a role for lithium and its elemental relatives in the biophysical mechanisms involved with the control of human blood cell production.