Carbohydrate and glycoprotein inhibitors of naturally occurring and induced agglutinins in the earthworm, Lumbricus terrestris

Immune defense and biological responses induced by toxics in Annelida

The phylum Annelida comprises primitive coelomates that possess specially developed cellular immunity against pathogens. Active phagocytosis by coelomocytes occurs in the struggle against bacteria in Polychaeta and Oligochaeta. Encapsulation plays an important role in defense against parasites, and experimental studies have demonstrated that cooperation between different coelomocyte populations occurs in this process. Spontaneous cytotoxicity of coelomocytes against xenogenic or allogenic cells is analogous with that of vertebrate natural killer cells. Graft rejection is a model for studying the activity of these cells. Accelerated rejection following multiple transplantation reveals that the cellular immune defense system has a short-term memory. In humoral immunity, agglutinins aggregate foreign material and their level is enhanced by antigens; in Annelida, however, no specificity analogous to vertebrate antibodies has been revealed, except for weak specificity of some antigen-binding proteins. Hemolytic substances have been detected, particularly in Oligochaeta, where a fetidin possesses bactericidal activity. Lysozyme and some antibacterial proteins also occur in Polychaeta. Annelida react to physical and chemical insults by various processes. These responses are mainly due to synthesis of stress-induced proteins, inhibition of enzyme activity, and modulation (inhibition or stimulation) of the activity of enzymes involved in the detoxification of xenobiotics. Moreover, these responses frequently differ from those of vertebrates, particularly in terms of the nature of inducers. In other respects, these responses are extremely variable in Annelida, even in closely related species.

Peptide fragments induce a more rapid immune response than intact proteins in earthworms

The effect of in vivo proteolytic processing of protein antigen was studied in Eisenia foetida earthworms. Parenteral administration of the protein antigen induces elevated levels of an antigen-binding protein (ABP) which recognizes the protein used for stimulation. When the protein antigen is administered simultaneously with nontoxic serine proteinase inhibitor, ABP levels remain close to background. On the other hand, the in vivo adaptive response of earthworms to peptide fragments obtained by coelomic fluid digestion of the foreign antigen occurs even in the presence of proteinase inhibitor and, moreover, is significantly faster as compared to the response to intact antigen. These findings confirm the role of proteolytic processing in earthworms. MALDI mass spectrometric analysis of the fragments after coelomic fluid digestion has revealed the presence of the peptide fragments with molecular weights in the mass range 700-1100 Da.