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

Objective: Histamine plays an important role in a series of processes inclu ding inflammation, allergy, gastric acid secretion, neurotransmission, embr yogenesis 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 mul tiple tissue factors, e. g. various cytokines and growth hormones. In this study the effect of interferon alpha and interferon yon the expression of H DC and on cell proliferation in vitro on melanoma cell line. Methods. We used recombinant human interferon alpha interferon gamma and hu man melanoma cell line HT168. Results: Our data show that both IFN alpha and IFN gamma decreased the HDC mRNA and protein expression, though with dissimilar kinetics. IFN gamma str ongly suppresses the proliferation at 72 h, while IFN alpha has a more mode rate effect. Conclusions. Since previously the inhibitory effect of histamine on gene ex pression of interferon gamma was detected, a reciprocal inhibition between histamine and IFN gamma is proposed.