The opsonic effect of carp complement on the phagocytosis by carp peritoneal neutrophils was investigated using antibody-sensitised sheep erythrocytes (EA) and baker's yeast (Y), which are the activators of the classical complement pathway (CCP) and the alternative complement pathway (ACP), respectively. Carp antibody (A) exerted little opsonic effect on the phagocytosis of sheep erythrocytes (E). The treatment of EA and Y with normal carp serum (C) greatly enhanced phagocytosis. Such opsonic effect is apparently due to the complement being activated via CCP and ACP, because the treatment of EA and Y with C3-depleted carp serum produced no effect. It was also found that the treatment of EAC and YC with the Fab fragment of anti-carp C3 (rabbit IgG) abolished the opsonising effect of carp complement deposited on the target cells. These results indicate that C3 is the major phagocytosis-promoting factor (opsonin). In addition, it was also demonstrated that pretreatment of the neutrophil surface with trypsin greatly decreased the phagocytosis of EAC, suggesting the presence of C3 receptors on the neutrophil surface.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Aquatic Science