ANTIGENIC CHARACTERIZATION OF HEMOCYTE SUBPOPULATIONS IN THE MUSSEL MYTILUS-EDULIS BY MEANS OF MONOCLONAL-ANTIBODIES

In order to characterize in more detail hemocytes from Mytilus edulis and establish links between histological and cytological features, mon oclonal antibodies (MABs) were prepared using hybridoma technology. Fi ve MABs were identified and their reactivity patterns were analyzed wi th both immunoperoxidase and ultrastructural immunogold labelling. Fou r MAB classes were identified by their immunostaining patterns. Optica l and ultrastructural examination revealed that Class I MAB reacted sp ecifically with basophilic granulocytes (granulocytes containing small granules). Class II and III MABs differed in the intensity of their i ndirect immunofluorescence and degree of immunoperoxidase labelling, b ut all recognized both basophilic and eosinophilic granulocytes. Epito pes recognized by Class IV MABs were not always present in basophilic granulocytes, whereas they were always expressed in the eosinophilic g ranulocytes (granulocytes containing large granules) and could constit ute differentiation antigens which progressively form during the matur ation process. Molecular weights of the proteins recognized by these M ABs were determined by Western blotting. It is concluded that immunost aining can identify at least three hemocyte types in M. edulis.