Histamine influences the expression of the interleukin-6 receptor on human lymphoid, monocytoid and hepatoma cell lines.

Based on our earlier data on the enhancing effect of histamine on the action of interleukin-6 (IL-6), we have studied the molecular mechanisms of these interactions. The effect of histamine was investigated on the binding of 125I-IL-6 by B lymphoma cell line CESS, monocytoid cell line U937 and hepatoma cell line HepG2. Histamine increases the IL-6 binding by CESS cells and inhibits that by U937 and HepG2 cells. Using H1 receptor (cetirizin and loderix) and H2 receptor (cimetidine and ranitidine) specific antagonists, an H1-dependent stimulation of IL-6 binding by CESS cells was found. In contrast, down-regulation of IL-6 binding by histamine was clearly mediated through H2 receptors. On U937 cells, using a monoclonal antibody reacting with the 80 kd chain of the human IL-6 receptor, and H2-receptor mediated inhibition of IL-6 receptor expression was found by FACS analysis.