Chronic relapsing experimental allergic encephalomyelitis. Cytotoxicity effected by a class II restricted T cell line specific for an encephalitogenic epitope.

We have examined the possibility that Ag-specific CTL responses may play a role in the pathogenesis of CREAE by using an effector T cell line (LN400) specifically reactive to the SJL encephalitogenic epitope defined by myelin basic protein MBP residues(90-101). The LN400 cell line was capable of adoptively transferring CREAE to naive SJL mice and proliferated specifically to synthetic peptides corresponding to MBP residues(90-101) and an N-acetylated analogue of this epitope, as well as MBP. Moreover, the cell line generated Ag-specific CTL responses only against syngeneic targets that had been pulsed with these Ag. Targets pulsed with irrelevant Ag were not lysed. These CTL responses were MHC restricted to H-2s and were inhibited if targets were preincubated with mAb specific for relevant class II Ag. No inhibition was seen if targets were preincubated with mAb specific for class I Ag, indicating that the CTL responses generated by this L3T4+ Lyt-2.2- cell lines were class II restricted. Studies designed to detect nonspecific CTL through a bystander mechanism failed to demonstrate significant lysis of bystander targets by this Ag-specific cell line. These findings have relevance in defining potential mechanisms of disease induction in this model autoimmune disease.