Histamine and the response to IFN-alpha in chronic hepatitis C.

Whole blood concentrations of histamine were examined in 20 patients with chronic hepatitis C after longterm treatment with interferon-alpha (IFN-alpha). In 13 of these patients, a transient (n = 5) or sustained (n = 8) normalization of liver enzymes and elimination of viral RNA were noted at the end of therapy. Seven patients did not respond to IFN-alpha. Nonresponding patients had significantly lower histamine levels in blood than transient (p = 0.0005) or sustained (p = 0.04) responders. Histamine levels were not different in patients with a sustained vs. a transient IFN response. Confounding factors, such as ongoing viral replication or liver cirrhosis, did not account for the differences in histamine levels. Our data suggest that hypohistaminism in peripheral blood may determine a poor response to IFN-alpha in chronic hepatitis C.