Identification of phagocytic cells, NK-like cytotoxic cell activity and the production of cellular exudates in the coelomic cavity of adult zebrafish

Coelomic cavity (CC) cells of mature zebrafish harvested by lavage with media or trypsin–EDTA contained 0.80–1.20 × 105 and 2.0–3.5 × 105 cells, respectively. Media lavage was composed of granulocytes (60–80%), lymphocytes (10–20%), and NCC (4–10%). Granulocytes had large electron dense cytoplasmic paracrystalline granules and a segmented nucleus; they expressed plastin-1, myeloid specific peroxidase and MCSF mRNA; and they were NCAMP-1+. Lymphocytes had B- and T-cell specific mRNA and were NCAMP-1− and NCCRP-1−. NCC were 3 μm, NCAMP-1+ and NCCRP-1+ and did not express B- and T-cell specific mRNA. Additionally, trypsin lavage contained monocytes (marginated chromatin, low nuclear:cytoplasm ratio, sparse cytosolic granules) and macrophages (non-segmented nuclei, no margination of chromatin, abundant electron dense granules). E. coli injected into the CC were phagocytosed in a dose and time dependent fashion by granulocytes, monocytes and macrophages. NCC lysed mammalian target cells and NCAMP-1 expressing hybridoma cells in redirected lysis assays.