Stimulation of various functions in murine peritoneal macrophages by high mannuronic acid-containing alginate (HMA) exposure in vivo

High mannuronic acid-containing alginate (HMA) was tested to affect murine peritoneal macrophages. Tn the present study, we measured various Functions of murine peritoneal macrophages that were isolated 20 h after intraperito neal injection with I-IMA (25 and 100 mg/kg). HMA increased the number of p eritoneal macrophages and phagocytosis. Macrophages from HMA-treated mice s ignificantly inhibited growth of rumor cells compared to macrophages from c ontrol mice. In addition, supernatants from macrophages of HMA-treated mice contained nitric oxide (NO), hydrogen peroxide (H2O2) and TNF-alpha. The i ncreased production of these cytotoxic molecules induced by HMA is consiste nt with tumoricidal activity of activated macrophages. Furthermore, HMA-ind uced tumoricidal activity was partially abrogated by anti-TNF-a, inhibitors of NO and the scavenger of reactive oxygen. Thus, the tumoricidal activity induced by HMA appeared to be mediated by the production of TNF-alpha, NO and H2O2. Taken together, these results suggest that HMA has the immunostim ulating effect on macrophages after in vivo exposure of it. (C) 2001 Elsevi er Science B.V. All rights reserved.