The zebrafish coelomic cavity

Abstract

The zebrafish (Danio rerio) is an emerging model in immunological and developmental studies. One of the practical limitations in this model is the ability to obtain immune cells in sufficient quantity. The zebrafish spleen contains about 100,000 leukocytes and the entire anterior and trunk kidney contains about 10 cells, 40% of which are red blood cells. A coelomic cellular exudate was observed following injections of adult zebrafish with LPS and fixed bacteria. Fish injected with Edwardsiella ictaluri also produced large exudate responses. Exudate cells were identified consisted of granulocytes, macrophages, lymphocytes, and nonspecific cytotoxic cells. Functional assays showed that the exudates contained cytotoxic activity against HL-60, YAC-1, and K562 targets. The granulocytes in these exudates phagocytosed Gram-positive and negative bacteria. We conclude that the zebrafish coelomic cavity is an immune responsive tissue appropriate for determination of host innate and adaptive immunity to infectious diseases.q