Coelomic Fluid Proteins as Basic Components

 of Innate Immunity in Earthworms

Ellen Kauschke

Ernst Moritz Arndt University Greifswald, Institute of Anatomy and Cell Biology, Fr. Loeffler Strasse 23c, 17487 Greifswald, Germany

The coelomic fluid (CF) of earthworms contains cells and many molecular components involved in innate immunity of these species. Among those are glycoproteins of lectin character which contribute to the recognition of foreign material in the coelomic cavity by binding to carbohydrates. Moreover they cause its  immobilisation by agglutination and destruction by membrane lysis. Further humoral components phenoloxidase, proteases and other enzymes are mainly involved in the elimination of foreign material.

Based on the analysis of several  earthworm species (Allolobophora chlorotica, Apporectodea caliginosa, Dendrodrillus rubidus, Eisenia fetida, Lumbricus rubellus, L. terrestris) we showed that wounding as well as the injection of foreign material into the coelomic cavity increases coelomocyte numbers and the activity of  some easily measurable humoral immune factors like proteases, agglutinins and lysins. Moreover newly synthesised proteins were identified within the protein pattern of CF after challenging, suggesting their involvement in immune reactions. Differences in protease activity become obvious especially by comparing enzyme patterns of untreated and stimulated CF samples separated by electrophoresis. Earthworm CF proteases are relatively heat stable, posses an activity optimum at neutral to basic pH and are classified mainly as serine proteases, presumably involved in melanization and phenoloxidase activation. The naturally occurring titre of the hemagglutinating activity varies among the earthworm species investigated but was generally increased after stimulation. An enhanced lytic activity was evident for some species after stimulating the immune response. Taking all these facts it can be summarised that disturbance of the homeostasis in earthworms results in an increased immune response. Some of these immune proteins might be considered as suitable bio-markers in monitoring environmental conditions. Protease pattern and protease activity may assumed to be promising candidates in this regard and are easy to analyse.