MANNAN DECELERATES THE CLEARANCE OF HUMAN RED-BLOOD-CELLS IN SCID MOUSE

Mannans and its related compounds decelerated human (Hu) red blood cel l (RBC)-clearance in severe combined immunodeficiency (SCID) mice by i nhibiting erythro-phagocytosis of macrophages. Chimeric SCID mice for Hu-RBC which are generated by repeated transfusions with mature Hu-RBC s are described recently as a model for Plasmodium falciparum infectio n, though the Hu-RBC clearance in the mice at present is very rapid an d the parasitemia in the mice is only erratic, Here, we aimed to study the method to decelerate Hu-RBC clearance in SCID mice, to establish a suitable mouse model for malaria parasites. Yeast and Candida mannan s as well as lactoferrin, a glycoprotein containing both oligomannosid e- and N-acetyllactosamine-type glycans, decelerated Hu-RBC clearance, but instead other saccharides such as carboxymethyl chitin, N-acetylg lucosamine, and D-glucose did not. Yeast mannan and lactoferrin interf ered significantly with in vitro Hu-RBC-phagocytosis which was also in hibited by mannopentaose and mannotoriose. D-mannose exhibited a moder ate inhibitory activity. N-acetyl-D-glucosamine, however, showed only a slight inhibitory activity, but D-glucose had no inhibitory activity on Hu-RBC phagocytosis. These results may postulate that Hu-RBC clear ance in SCID mouse might be mediated by receptor-ligand binding by a m acrophage lectin like receptor with mannose specificity. (C) 1998 Else vier Science B.V.