Reduced susceptibility of T cell-deficient rats to induction of experimental allergic neuritis.

Lewis rats were made deficient in T cells by adult thymectomy and lethal irradiation, and then reconstituted with T cell-free bone marrow. Their ability to develop experimental allergic neuritis (EAN) was compared with normal rats. The majority of T cell-deficient rats remained clinically and histologically unaffected, whereas all but one of the normal rats developed severe EAN. Those T cell-deficient animals which succumbed to EAN were found to have a significantly higher percentage of residual blood T lymphocytes than those which did not. Full susceptibility to EAN was restored by an inoculum of whole thoracic duct lymphocytes (TDL) from normal animals but not by TDL depleted of T cells. The results therefore provide direct confirmation that T cells are a requirement for the development of EAN.