CD28 and demyelinating disease: To further understand the potential role of FoxP3+CD4+ T cells in the pathogenesis of TMEV-induced demyelinating disease, we generated activated VP2-TCR-Tg FoxP3+CD4+ T cells in vitro using a mixture of retinoic acid, TGF-β, IL-2, and a T cell stimulant (VP272-86 or anti-CD3/CD28 antibodies), as previously described [28,29].