Toxicology Letters 119 (2001) 173 – 181 Role of corticosterone in ethyl carbamate-induced immunosuppression in female BALB/c mice Shin Woo Cha a , Hu Jang Lee b , Myung Haing Cho b , Mun Han Lee b , Woo Suk Koh a , Sang-Seop Han a , Jung-Ae Kim c , Eung-Seok Lee c , Doo-Hyun Nam c , Tae Cheon Jeong c, * a Toxicology Research Center, Korea Research Institute of Chemical Technology, P.O. Box 107, Yusung, Taejon 305 -606, South Korea b College of Veterinary Medicine, Seoul National Uniersity, Suwon 441 -744, South Korea c College of Pharmacy, Yeungnam Uniersity, 214 -1 Dae -dong, Kyungsan, Kyungbuk 712 -749, South Korea Received 28 August 2000; received in revised form 23 November 2000; accepted 24 November 2000 Abstract We have recently demonstrated that the antibody response to the T-cell-dependent antigen, sheep red blood cells (SRBCs), was suppressed by ethyl carbamate 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 increased dose-dependently. To investigate the possible role of corticosterone in ethyl carbamate-induced immunosuppression, the antibody response to SRBCs and the subpopulation changes of spleno- cytes and thymocytes were determined 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 thymus weights and/or the increase in the level of serum corticosterone. Meanwhile, the antibody response was not suppressed by ethyl carbamate in the ADX 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 mice. The flow cytometric analyses on thymocytes did not show obvious differences as seen in the spleen. Finally, when the ADX mice were treated intraperitoneally with 25 mg/kg corticosterone, the antibody response was significantly suppressed. Taken together, our present results suggested that corticosterone might be, at least partially, responsible for ethyl carbamate-induced immunosuppression in female BALB/c mice. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Ethyl carbamate; Corticosterone; Immunosuppression; Adrenalectomy; Antibody response; Flow cytometry www.elsevier.com/locate/toxlet * Corresponding author. Tel.: +82-53-8102819; Fax: +82-53-8113871. E-mail address: taecheon@yu.ac.kr (T.C. Jeong). 0378-4274/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S0378-4274(00)00306-4