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

Serotonin is a well-known neurotransmitter and neuroimmunomodulator wh ich has been reported to modulate T cell and NK cell proliferation, In this study we investigated whether serotonin could regulate mitogen-s timulated proliferation of the mature B lymphocyte, Mouse and rat sple en 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 proliferat ion in a dose- and time-dependent manner, These effects were reproduce d 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-HT 1A receptor antagonists (+)WAY 100135 and propranolol, Moreover, lipop olysaccharide-activated mouse spleen cells expressed specific binding sites for [H-3]8-OH-DPAT, These results show that serotonin upregulate s mitogen-stimulated B lymphocyte proliferation through B-HT1A recepto rs, thus providing an important link between this neurotransmitter and the immune system. (C) 1995 Academic Press, Inc.