Central Role of Th2 and Tc2 Lymphocytes in Multiple Sclerosis Pattern II Demyelinating Lesions

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system with marked heterogeneity in several aspects including pathological processes. Four histopathological patterns of MS have been described. Pattern II is characterized by antibody and complement deposition. MS is considered a prototypic T cell-mediated disease, but until now the study of pathogenic T cells has encountered major challenges, most importantly the limited access of brain-infiltrating T cells. Here, we used next generation sequencing to identify clonally expanded T cells in demyelinating pattern II brain autopsy lesions and subsequently isolated these as T cell clones from autologous cerebrospinal fluid. The functional characterization shows that T cells releasing Th2 cytokines and able to provide B cell help dominate the T cell infiltrate in pattern II brain lesions. Our data provide the first functional evidence for a role of Th2/Tc2 cells in pattern II MS. Two stimulated CD4+ Th2 brain infiltrating T cell clones compared with stimulated circulaiting memory CD4+ T cells and two stimulated CD8+ T cell clones (one Tc1 and one Tc2) compared with each other.