Increased expression of p53 and Bax in the spinal cords of rats with experimental autoimmune encephalomyelitis

The expression of pro-apoptotic molecules p53 and Bax in the spinal cord of rats with experimental autoimmune encephalomyelitis (EAE) was examined. Apoptosis was confirmed by the terminal deoxynucleotidyl transferasemediated dUTP nick end-labeling (TUNEL) method. TUNEL (1) apoptotic cells were mainly either ED1 (1) macrophages or T-cells in the parenchyma of EAE. Western blot analysis showed that both p53 and Bax expression significantly (P , 0:01) increased in the spinal cords of EAE rats at the peak stage, and thereafter declined. An immunohistochemical study showed that inflammatory cells (notably T cells) in the parenchyma express p53 and Bax, while brain cells, including neurons and glia, were devoid of nuclear staining for these molecules. The nuclear expression of p53 largely matches apoptotic cells in the parenchyma of EAE. These findings suggest that the pro-apoptotic molecules p53 and Bax may play an important role in eliminating T cells in the parenchyma in EAE. q 2000 Elsevier Science Ireland Ltd. All rights reserved.