Falcão et al. demonstrated that OPCs cultured in the presence of MOG35–55 peptide and CD4+ T cells expressing the T cell receptor for MOG35–55 were able to induce the proliferation of naïve, memory, and activated T cells, indicating that OPCs can execute antigen presentation via MHC-II, a process especially relevant in the context of MS. Here, CD4 is linked to myeloid sarcoma.