Differential modulation of nitric oxide production by curcumin in host macrophages and NK cells

Curcumin, the yellow pigment from Curcuma longa, has been shown to possess tumoricidal activity. We have earlier reported the induction of apoptosis i n AK-5, rat histiocytic cells by curcumin leading to the inhibition of tumo r growth in vivo. In this study me have observed differential activation st atus in host macrophages and NK cells induced by curcumin during the sponta neous regression of subcutaneously transplanted AK-5 tumors. Closer scrutin y of the cytokine profile and nitric oxide (NO) production by immune cells showed an initial downregulation of Th1 cytokine response and WO production by macrophages, and their upregulation in NK cells, which picked-up upon p rolonged treatment with curcumin, culminating in a stronger tumoricidal eff ect. These studies suggest that the host macrophages and NK cells play an i mportant modulatory role in the remission of AK-5 tumor. (C) 2000 Federatio n of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.