Development of long-term rainbow trout spleen cultures that are haemopoietic and produce dendritic cells

Different tissue dissociation protocols and serum supplements resulted in a variety of primary cultures from rainbow trout spleens. These were classified as either haemopoietic or non-haemopoietic. In haemopoietic cultures, a complex stromal layer developed on the cell culture surface; round cells appeared on the stromal layer; and ultimately some round cells were released into the medium as a non-adherent population. Many non-adherent cells were able to reattach in new culture vessels. Most of these had the characteristic shape and unique motility of dendritic cells. Cultures of these cells were subcultivated 2–4 times but continuous cell lines did not arise. Haemopoietic cultures resulted with collagenase dissociation and maintenance in high foetal bovine serum (FBS) concentrations. Non-haemopoietic cultures contained adherent cells, including macrophages and fibroblasts, but did not develop a non-adherent population. These cultures resulted with 10% FBS or horse serum and after explant outgrowth or dissociation with trypsin. Both culture types should be useful for studying the regulation of haemopoiesis and the functions of specific immune cells in fish.