Role of corticosterone in ethyl carbamate-induced Immunosuppression in female BALB/c mice

We have recently demonstrated that the antibody response to the T-cell-depe ndent antigen, sheep red blood cells (SRBCs), was suppressed by ethyl carba mate in female BALB/c mice. At the same doses, ethyl carbamate decreased in the numbers of splenic macrophages, B cells, total T cells, CD4(+) T cells and CD8(+) T cells. In addition, the serum level of corticosterone was inc reased dose-dependently. To investigate the possible role of corticosterone in ethyl carbamate-induced immunosuppression, the antibody response to SRB Cs and the subpopulation changes of splenocytes and thymocytes were determi ned in naive, sham-operated and adrenalectomized (ADX) female BALB/c mice. When the mice were treated intraperitoneally with 400 mg/kg ethyl carbamate , the antibody response was significantly suppressed by ethyl carbamate in naive and sham-operated mice in accompanying the decrease in spleen and thy mus weights and/or the increase in the level of serum corticosterone. Meanw hile, the antibody response was not suppressed by ethyl carbamate in the AD X mice. The splenic numbers of total cells, macrophages, B and T cells, and CD4(+) cells were decreased by ethyl carbamate in naive and sham-operated mice. Meanwhile, each cell number was comparable with control in the ADX mi ce. The flow cytometric analyses on thymocytes did not show obvious differe nces as seen in the spleen. Finally, when the ADX mice were treated intrape ritoneally with 25 mg/kg corticosterone, the antibody response was signific antly suppressed. Taken together, our present results suggested that cortic osterone might be, at least partially, responsible for ethyl carbamate-indu ced immunosuppression in female BALB/c mice. (C) 2001 Elsevier Science Irel and Ltd. All rights reserved.