Histamine Inhibits Interleukin 1 Production by Lipopolysaccharide‐Stimulated Human Peripheral Blood Monocytes

Histamine inhibited the production of interleukin 1 (IL-1) induced by lipopolysaccharide (LPS) in cultures of purified human peripheral blood monocytes. The effect of histamine on IL-1 production was dose-dependent and significant at histamine concentrations of 10(-4)-10(-5) M. The histamine H2 receptor agonists dimaprit and 4-methylhistamine, but not the H1 receptor agonists 2-pyridylethylamine, aminoethylthiazole and 2-methylhistamine, modulated the IL-1 production in a similar manner to histamine. The inhibitory effects of histamine could be reversed by the H2 receptor antagonist cimetidine but not by the H1 receptor antagonist mepyramine. This indicates that the inhibitory effects of histamine on LPS-induced IL-1 production are mediated through H2 receptors on human peripheral blood monocytes.