Both interferon (IFN)alpha and IFNgamma inhibit histidine decarboxylase expression in the HT168 human melanoma cell line

Histamine plays an important role in a series of processes including inflammation, allergy, gastric acid secretion, neurotransmission, embryogenesis and in various tumours. Histidine decarboxylase (HDC), the enzyme solely responsible for generation of histamine is expressed in many cells including regenerating and tumour cells. HDC expression is regulated by multiple tissue factors, e.g. various cytokines and growth hormones. In this study the effect of interferon alpha and interferon gamma on the expression of HDC and on cell proliferation in vitro on melanoma cell line. We used recombinant human interferon alpha, interferon gamma and human melanoma cell line HT168. Our data show that both IFNalpha and IFNgamma decreased the HDC mRNA and protein expression, though with dissimilar kinetics. IFNgamma strongly suppresses the proliferation at 72 h, while IFNalpha has a more moderate effect. Since previously the inhibitory effect of histamine on gene expression of interferon gamma was detected, a reciprocal inhibition between histamine and IFNgamma is proposed.