Role of T lymphocytes in the pathogenesis of experimental autoimmune encephalomyelitis

A dichotomy between clinical and histological signs of experimental autoimmune encephalomyelitis (EAE) was demonstrated in neonatally thymectomized (NNTx) rats. Although neonatal thymectomy prevented subsequent induction of clinical EAE in Lewis rats challenged as young adults with syngeneic basic protein (BP) of myelin, there was a 50% incidence of histological EAE. Both cellular and humoral immune responses to BP were reduced in the BP rats. However, the presence of a cell mediated response to BP (MIF release) was statistically associated with the occurrence of histological EAE. Diminished preimmunization blood lymphocyte counts and impairment of the response of spleen cells to phytohemagglutinin were associated with reduced antibody responses. This suggests that collaboration between T and B cells may be necessary for production of antibody to BP. The relationship between antibody and clinical EAE is not clear and warrants further investigation.