Antibiotics and cell-mediated immunity in fish -: In vitro study

The effect of chloramphenicol and florfenicol on fish T and B cell proliferation and polymorphonuclear (PMN) and mononuclear (MN) cell phagocytic ability was determined. Cells were isolated from head kidney and spleen of 20 fish (Cyprinus carpio). Antibiotics were administered in vitro at concentrations of 20 and 40 mu/ml. All determinations were performed in nine repetitions. T and B cell proliferation after application of the drugs was evaluated by a spectrophotometric method with lipopolysaccharide and concanavalin A as mitogens. Under the conditions used in this study the following results were achieved: chloramphenicol and florfenicol at a concentration of 40 mu/ml reduced proliferation of T and B cells, although effect of the first one was stronger. We found that both antibiotics were more toxic for B than for T cells. Neither chloramphenicol nor florfenicol at a concentration of 20 mu/ml altered lymphocyte proliferation. The influence of the antibiotics on PMN and MN cell phagocytic ability was determined by the respiratory burst activity test based on measurement of the nitro blue tetrazolium reduction, which allowed to detect intracellular O-2. Chloramphenicol and florfenicol at a higher dose depressed phagocytic ability of PMN and MN cells. Moreover the cells isolated from spleen were more sensitive to suppressive activity of the drugs than those isolated from head kidney. No effects were observed for chloramphenicol and florfenicol at a concentration of 20 mu/ml. Results indicated that the lower dose of the anibiotics does not diminish lymphocyte proliferation or PMN and MN cell phagocytic ability, while the higher dose does alter both of studied parameters.