The role of opsonin in phagocytosis by coelomocytes of the earthworm

The phagocytes which reside in the coelomic cavity of the earthworms have roles in cellular immunity. The phagocytic activity of coelomic cells of the earthworm Dendrobaena veneta against the pathogenic and non-pathogenic bacteria was investigated in vitro. The coelomic cells of D. veneta having phagocytic activity was separated by density gradient centrifugation method. It was observed that these cells have neutrophil and basophil structure. Among the pathogenic bacteria, B. megaterium and A. hydrophila, and non-pathogenic bacteria P. maltophilia and B. subtilis, to various earthworms, B. megaterium was significantly ingested by phagocytes (p<0.05). It was observed that the optimum period for the bacterial phagocytosis of D. veneta phagocytic cells is 60 minutes and that differences in temperatures had no any visible effect on the phagocytosis itself. No significant difference was observed between all the tested bacteria with opsonin. Instead, phagocytosis of B. megaterium was remarkably inhibited when crude coelomic fluid of D. veneta was used as an opsonin