Mitogen-induced proliferation of trout kidney leucocytes by one-step culture in fibrin clots.

This work describes a trout kidney leucocyte mitogen-stimulation assay using fibrinogen/thrombin. Cloning was obtained by only one step instead of by two steps, as required by the agar method described to date. Cultures were stimulated not only with phytohemagglutinin (PHA) and Escherichia coli lipopolysaccharides (LPS) but also with Concanavalin A (Con A) and six LPS from aquatic pathogenic bacteria. The number of colony-forming cells detected, and their morphological type depended on the mitogen, the time of incubation and the trout. PHA was the best inducer of trout kidney leucocyte colony formation followed by Con A, giving rise to four different homogeneous types of colonies formed by large-nucleated cells, cells with eccentric nuclei, multinucleated cells and lymphocytes.