Myelopoietic response in tumour-bearing mice by an aggregated polymer isolated from Aspergillus oryzae

The effects of magnesium ammonium phospholinoleate-palmitoleate anhydride ( MAPA), a proteic aggregated polymer isolated from Aspergillus oryzae, on th e growth and differentiation of granulocyte-macrophage progenitor cells (co lony-forming unit-granulocyte-macrophage [CFU-GM]) in normal and Ehrlich as cites tumour-bearing mice were studied. Myelosuppression concomitant with i ncreased numbers of spleen CFU-GM was observed in tumour-bearing mice. Trea tment of these animals with MAPA (0.5 - 10 mg/kg) stimulated marrow myelopo iesis in a dose-dependent manner and reduced spleen colony formation. No ch anges were observed in total and differential marrow cell counts. The dose of 5.0 mg/kg MAPA, given prior or after tumour inoculation, was the optimal biologically active dose in tumour-bearing mice and this dose schedule als o stimulated myelopoiesis in normal mice. MAPA significantly enhanced survi val and concurrently reduced tumour growth in the peritoneal cavity. We pro pose that the modulatory effect of MAPA on the myelopoietic response may be related to its antitumour activity as a possible mechanism for regulation of granulocyte-macrophage production and expression of functional activitie s. (C) 2000 Elsevier Science B.V. All rights reserved.