Natural Killer Cell Activity, Lymphocyte Proliferation, and Cytokine Profile in Tumor‐Bearing Mice Treated with MAPA, a Magnesium Aggregated Polymer from Aspergillus oryzae

Abstract

The present study examined the effects of MAPA, an antitumor aggregated polymer of protein magnesium ammonium phospholinoleate‐palmitoleate anhydride, isolated from Aspergillus oryzae, on concanavalin A (Con A)‐induced spleen cell proliferation, cytokine production and on natural killer (NK) cell activity in Ehrlich ascites tumor‐bearing mice. The Ehrlich ascites tumor (EAT) growth led to diminished mitogen‐induced expansion of spleen cell populations and total NK activity. This was accompanied by striking spleen enlargement, with a marked increase in total cell counts. Moreover, a substantial enhancement in IL‐10 levels, paralleled by a significant decrease in IL‐2 was observed, while production of IL‐4 and interferon‐γ (IFN‐γ) was not altered. Treatment of mice with 5 mg/kg MAPA for 7 days promoted spleen cell proliferation, IL‐2 production and NK cell activity regardless of tumor outgrowth. In addition, MAPA treatment markedly enhanced IFN‐γ levels and reduced IL‐10 production relative to EAT mice. A 35% reduction in splenomegaly with normal number of nucleated cells was also found. Altogether, our results suggest that MAPA directly and/or indirectly modulates immune cell activity, and probably disengages tumor‐induced suppression of these responses. Clearly, MAPA has an impact and may delay tumor outgrowth through immunotherapeutic mechanisms.

Key Words :

• Ehrlich tumor
• NK cell activity
• IL‐2
• IFN‐γ IL‐10
• IL‐4
• MAPA
• Proteic aggregated polymer of magnesium ammonium phospholinoleate‐palmitoleate anhydride