Studies on lectins of amago (Oncorhyncus rhodurus). I. Amago ova lectin and its receptor on homologous macrophages.

A lectin was found in the ova of amago, a Japanese trout (Oncorhyncus rhodurus), which agglutinates rabbit, rat and human B-type erythrocytes. The hemagglutination was specifically inhibited by monosaccharides, L-rhamnose, D-galactose, and their C2 and C4 analogs, and p-nitrophenyl-alpha-D-galactoside and melibiose, indicating a binding specificity for alpha-L-rhamnosyl or alpha-D-galactosyl type sugar moiety. To study its interaction with homologous cells, amago peritoneal macrophages were isolated from corn starch-stimulated peritoneal exudates. The lectin-rabbit erythrocyte complexes were found to adhere onto the macrophages harvested on the 4th day or later after the stimulation, but not to those obtained within 3 days; the latter macrophages acquired the complex-binding capacity when cultured for 3 to 4 days in vitro. These findings indicated that a lectin receptor is expressed on peritoneal macrophages after inflammatory stimulation. Similar lectin receptor-bearing macrophage-like-cells were also detected during in vitro amago head kidney culture. This suggested that the inflammatory induced peritoneal macrophages may be differentiated from the head kidney macrophage precursor cells and during this process the ova lectin receptors also become expressed.