The fate of protein antigen in earthworms: study in vitro.

Earthworm coelomocytes digest protein antigen in vitro. Proteolytic activity was detected both in cell-free coelomic fluid and in cell cultures of free coelomocytes which are effectors of earthworm immunodefense mechanisms. Antigen is cleaved either intracellularly or by proteolytic enzymes released by coelomocytes into the medium. Proteolysis was observed both in non-stimulated and antigen-stimulated cultures. Since significantly higher proteolysis was shown in supernatants from cultures of antigen-stimulated coelomocytes, we can assume that the release of proteolytic enzymes was inducible.