Effects of short-term lithium treatment on peripheral blood lymphocytes and granulocytes in healthy volunteers.

The effects of a short-term treatment with lithium carbonate on lymphocytes and granulocytes were studied in six normal subjects. The lithium effects are related to a direct, immediate and quickly reversible action of the drug on the bone marrow, as demonstrated by the granulocyte number and variations in Arneth's index. Although lymphocyte and granulocyte functions do not seem to be affected by lithium when investigated by the usual methods, the ability of the drug to counteract the theophylline-induced inhibition of cellular functions would suggest that lithium acts mainly through the modulation of intracellular levels of cyclic nucleotides. This is confirmed by evaluation of cellular cyclic 3',5'-adenosine monophosphate (cAMP). The above hypothesis could explain the quick onset and loss of lithium action on granulopoiesis.