Following this study, Wang and colleagues (72) showed that B cells from HLA-DR15+ MS patients can present self-peptide fragments derived from DR2a and DR2b that activate CD4 T cells and identified memory CD4 T cells in the CSF of MS patients that respond to DR2a or DR2b self-peptides presented by B cells and cross-react with RASGRP2, MBP and peptides from EBV and a commensal gut bacterium. The gene discussed is RASGRP2; the disease is myeloid sarcoma.