C3BI formation at the time of complement enhancement in malnourished rats

Abstract

We have investigated the ability of lentinan to increase host resistance to certain bacterial infection in malnourished states by enhancement of complement (C3) activity. It is considered that generation of C3b or C3bi is closely related to the activation of macrophages due to binding to complement receptor 3 (CR3) which is present on the surface of phagocytic and cytotoxic cells. We developed a novel method using an Immune Adherence Hemagglutination (IAHA) pattern to assess the formation of C3b and C3bi in vitro. The effect of complement activators was also evaluated. The C3b formation capacity of the sera was measured as IAHA pattern by the addition of dithiothreitol (DTT) which prevents C3bi formation by factors I and H and/or CR1. Formation of C3bi was considered as the range of difference between the end titers of IAHA with or without DTT. The administration of 2mg/kg and 6mg/kg of Znchlorophyllin and 2mg/kg of lentinan could enhance C3 levels and C3b and C3bi formation activities in malnourished rats. C3bi formation was closely related to the phagocytic activities of peritoneal macrophages. We also confirmed that the CR3 site on the surface of monocytes blocked by OKM1 monoclonal anti-CR3 antibody reduced phagocytosis of GEAC3bi particles. These results suggest that phagocytic activity or the clearance capacity of macrophages is enhanced through the interaction of macrophages and increased C3bi formation.