Cytotoxicity of T cells for cerebral endothelium in multiple sclerosis

We investigated the cytotoxic effect of peripheral blood T cells on cerebral endothelium in patients with MS. We examined in vitro the damage to 51Cr-labelled dissociated human brain endothelial cells produced by mitogen-stimulated T cell lines from patients with MS and controls. Endothelial targets were lysed by T-lymphocytes from patients with acute relapsing MS during an exacerbation at every target-effector cell ratio tested compared with controls (P < 0.001). The percentage of endothelial targets lysed was not significantly increased by incubation with T cells from patients with acute relapsing MS in remission and chronic progressive MS, compared with that of normal subjects. Relapsing MS patients during an exacerbation had significantly higher interleukin-1 (IL-1)-alpha concentrations in cultures of targets with effector cells than normal subjects (P < 0.02). Experiments of major histocompatibility complex (MHC)-restricted cytotoxicity in MS demonstrated incomplete blocking of specific lysis by either anti-MHC class I or class II monoclonal antibody (mAb). These results indicate that cytotoxicity of T cells for cerebral endothelial cells may play a role in the initiation of immune response in acute relapsing MS during an exacerbation which appears to cause an increase in blood-brain barrier (BBB) permeability.