Splenectomy and adoptive cell transfer reveal a prominent role for splenicmemory lymphocytes in the development of chronic relapsing experimental autoimmune encephalomyelitis

We previously reported that acute experimental autoimmune encephalomyelitis (EAE), induced by active immunization of SJL mice, could be converted into chronic relapsing EAE (CR-EAE) by a pretreatment with neuroantigen and kil led mycobacteria 2 months earlier. This finding indicates that immune memor y, established by the pretreatment, influences the subsequent EAE induction . The present study shows that splenectomy and lymphadenectomy, applied 1 w eek before the subsequent active immunization of the pretreated mice, effic iently abort the chronic nature of CR-EAE. Furthermore, we have found that adoptive transfer of lymphocytes from the spleen (but not of those from the local draining lymph nodes) of the pretreated mice to naive syngeneic reci pients 1 week before the acute EAE-induction immunization results in the de velopment of CR-EAE. On the other hand, the transfer of lymphocytes from th e local draining lymph nodes aggravates the acute disease. These data suppo rt a critical role for immune memory of the previous suboptimal challenge i n the development of chronic relapsing demyelinating disease.