ADHESION OF LYMPHOCYTES TO ENDOTHELIAL-CELLS IN EXPERIMENTAL ALLERGICENCEPHALOMYELITIS BEFORE AND AFTER TREATMENT WITH ENDOTOXIN LIPOPOLYSACCHARIDE

We investigated the in vitro adhesion of Cr-51-labeled lymphocytes to cultured brain endothelial cells and the in vivo expression of interce llular adhesion molecule-1 (ICAM-1) on cerebral endothelial cells in a rat model of experimental allergic encephalomyelitis (EAE) before and after treatment with lipopolysaccharide (LPS). Adhesion of lymphocyte s to cerebral endothelial cells was significantly increased in EAE com pared with controls (p<0.01), and was significantly correlated with th e percentage of major histocompatibility complex class II antigen-posi tive cells in lymph node cells (p<0.001). LPS enhanced ICAM-1 expressi on on endothelial cells and lymphocyte adhesion to those cells, and ca used a significant increase in the in vivo expression of ICAM-1 compar ed with controls (p<0.001). Lymphocyte adhesion to endothelial cells w as significantly blocked by monoclonal antibodies against ICAM-1, lymp hocyte function-associated antigen-1, or very late activation antigen- 4. Our findings suggest that lymphocyte adhesion to brain endothelial cells may contribute to lymphocyte migration across the blood-brain ba rrier in EAE and that LPS may cause progression of EAE lesions.