Th2 immune regulation induced by T cell vaccination in patients with multiple sclerosis.

T cell responses to myelin basic protein (MBP) are potentially involved in the pathogenesis of multiple sclerosis (MS). In this study, we demonstrated that subcutaneous inoculations with irradiated autologous MBP-reactive T cell clones (T cell vaccination) elicited CD8+ anti-idiotypic T cell responses and CD4+ Th2 cell responses in patients with MS. Both regulatory cell types induced by T cell vaccination contributed to the inhibition of MBP-reactive T cells while they differed in the recognition pattern and functional properties. We describe for the first time that the Th2 regulatory cells reacted with activated but not resting T cells in the context of MHC class II molecules and inhibited the proliferation of MBP-reactive T cells through the secretion of IL-4 and IL-10. The T-T cell interaction mediated by Th2 regulatory cells was independent of the antigen specificity of activated T cells. The findings have important implications for our understanding of the regulatory mechanism induced by T cell vaccination.