Treatment of established chronic relapsing experimental allergic encephalomyelitis with anti-L3T4 antibodies.

CR-EAE is an autoimmune T cell-mediated disease that can be induced in mice either by the injection of MSCH and CFA or by passive transfer of MBP-sensitized T cells. To evaluate the clinical relevance of anti-L3T4 antibodies in this relapsing, remitting disease, we studied the therapeutic benefits of such treatment on CR-EAE in animals when treatment was begun after the onset of initial paralytic signs. Animals treated biweekly with anti-L3T4 antibody had fewer relapses than control animals, and the histopathology of the brain and spinal cord showed fewer and less extensive lesions. Serial analysis of lymph node cell populations and antibody levels showed that animals treated with anti-L3T4 antibody had a depletion of the helper/inducer T cell population and did not develop a humoral response to the administered rat antibody. This study raises the possibility of treatment with antibodies against T cell subsets in established disease wherein this subset is known to play a crucial role.