Immunosuppressive effects of dexamethasone on spleen and head kidney cells from Arabian Sea bream (Acanthopagrus arabicus): in vitro model of environmental pharmaceutical pollution.

OBJECTIVE: Pharmaceuticals are emerging pollutants that have received great interest because of their discharge into aquatic ecosystems through wastewater worldwide. However, studies on the effects of these pollutants on aquatic animals are limited. Dexamethasone is a potent synthetic glucocorticoid with anti-inflammatory and immunosuppressive effects. Understanding how this medicine affects the immune response of fish was the topic of interest in the present study. The present study investigated the effects of dexamethasone on the innate immune response of the spleen and head kidney cells of Acanthopagrus arabicus in vitro.

MATERIALS: Cultured spleen and head kidney cells were exposed to dexamethasone with various concentrations in vitro. After 48 h, the toxic effects of dexamethasone on innate immune factors were assessed.

RESULTS: Based on the results, the sensitivity of cultured spleen and head kidney cells to dexamethasone increased in a concentration-dependent manner. Dexamethasone significantly decreased the number of IgM-secreting cells and IgM secretion. It also significantly reduced the C3 content of the cultivated cells but did not significantly alter the C4 and ACH50 contents or lysozyme activity of the cultivated cells. Furthermore, dexamethasone significantly suppressed respiratory burst activity and nitric oxide production in the spleen and head kidney cells.

CONCLUSIONS: In conclusion, the immunosuppressive effect of dexamethasone was due mainly to its suppressive effects on IgM-secreting cells and IgM production, C3 content, burst activity and nitric oxide production in the spleen and head kidney cells.