SEROTONIN UP-REGULATES MITOGEN-STIMULATED B-LYMPHOCYTE PROLIFERATION THROUGH 5-HT1A RECEPTORS

Serotonin is a well-known neurotransmitter and neuroimmunomodulator which has been reported to modulate T cell and NK cell proliferation, In this study we investigated whether serotonin could regulate mitogen-stimulated proliferation of the mature B lymphocyte, Mouse and rat spleen cells were cultured with serotonin in the presence or absence of a combination of Escherichia coli lipopolysaccharide and dextran sulfate, and proliferation was assessed by [H-3]thymidine uptake or propidium iodide staining of DNA, Serotonin alone had no effect on spleen cell proliferation, while it increased mitogen-stimulated B cell proliferation in a dose- and time-dependent manner, These effects were reproduced by the selective 5-HT1A receptor agonist 8-OH-DPAT, Serotonin- or 8-OH-DPAT-induced increase in proliferation could be blocked by the 5-HT1A receptor antagonists (+)WAY 100135 and propranolol, Moreover, lipopolysaccharide-activated mouse spleen cells expressed specific binding sites for [H-3]8-OH-DPAT, These results show that serotonin upregulates mitogen-stimulated B lymphocyte proliferation through B-HT1A receptors, thus providing an important link between this neurotransmitter and the immune system. (C) 1995 Academic Press, Inc.