APPLICATION OF DENSITY GRADIENT CENTRIFUGATION FOR SEPARATION OF EOSINOPHILIC AND BASOPHILIC HEMOCYTES FROM MYTILUS-EDULIS AND CHARACTERIZATION OF BOTH CELL GROUPS

Different discontinuous Percoll gradients were developed to separate native as well as alcohol- or formaldehyde fixed hemocytes of Mytilus edulis into basophilic and eosinophilic cell fractions by density gradient centrifugation, The purity of the isolated cell groups ranged from 84% to 99% and was dependent on the pretreatment of the hemocytes, The percentage of both cell types differed strongly between Mytilus specimens, Hemolymph from individual mussels (n = 56) contained 14-87% of basophils (mean +/- SD = 57 +/- 12.9%). Basophilic cells had a diameter of 4-14 mu m, the majority measuring 9-11 mu m; eosinophilic cells had a;diameter of 7-19 mu m, the majority being 11-13 mu m, Only eosinophils bound preoxidized 3-amino-9-ethylcarbazole (AECox) and varying percentages of them possessed phenoloxidase activity, Furthermore, differing numbers of eosinophils secreted cytotoxic molecules, Cell extracts derived from isolated basophils and eosinophils exhibited reproducible differences in their protein pattern after separation in SDS-PAGE under reducing conditions.