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

Parenteral administration of antigen induces in the earthworms Lumbricus terrestris and Eisenia foetida the formation of antigen-binding protein. Labelled antigen was efficiently digested in the coelomic fluids of both species since the total amount of radioactivity in the coelomic fluids decreased. Antigen internalized in the free coelomocytes of both species was present in a TCA-precipitable form, although the decline of total radioactivity was higher than in the coelomic fluid, indicating that the TCA-nonprecipitable fragments are rapidly released from coelomocytes into the coelomic fluid. Within the first 24 h after administration, labelled antigen was detected throughout all tissues except for the epidermis and cuticle, and after 4 days it was found in the chloragogenic tissue around the gut, dorsal vein and typhlosole.