SEROTONIN, SEROTONINERGIC AGENTS AND THEIR ANTAGONISTS SUPPRESS HUMORAL IMMUNE-REACTION IN-VITRO

Serotonin(5-HT), its derivative 5-methoxy-tryptamine (MeOT) and ergot- alkaloid dihydroergosine (DHESN) suppressed the immune reaction of mou se spleen cells against sheep erythrocytes in vitro (PFC assay). Ketan serin and propranolol, antagonists of 5-HT, also caused suppression. H owever, cells incubated with propranolol 20 min before 5-HT or MeOT pr oduced as many plaques as the non-treated cells. Preincubation with ke tanserin resulted in similar interference, but the reversal was not co mplete. It is concluded that serotonin and related agents probably aff ect several types of immunocompetent cells participating in successive stages of the PFC reaction. The antagonists probably interfered via 5 -HT receptors, adrenergic receptors or both. Immunosuppression observe d with serotoninergic agents and their antagonists draws attention to possible side effects of such drugs.