Decreased agonist-stimulated Ca2+ response in neutrophils from patients under chronic lithium therapy

The agonist-stimulated increase in the intracellular concentration of free Ca2+ ([Ca2+]i) was determined in neutrophils from patients under chronic lithium therapy and a control group of age- and sex-matched healthy drug-free subjects. Cells were stimulated with the chemotactic peptide formylmethionylleucylphenylalanin (fMLP) and the Ca2+ concentrations measured with the fluorescent Ca2+ indicator Fura-2. The Ca2+ response to stimulation with fMLP was significantly attenuated in neutrophils from patients chronically treated with lithium. The data suggest that lithium treatment inhibits the inositol phospholipid second messenger generating system in human cells and support the results of earlier inositol phosphate measurements in fMLP-stimulated neutrophils.