CD28 and myeloid sarcoma: Given that many cell types (i.e., CD8+ and CD4+ T cells and NK cells) produce IFN-γ and IL-17 (27) and that Th1 and Th17 cells are considered key players in the immunopathogenesis of MS, we analyzed the frequency of Th1 and Th17 cells in a subset of MS patients after ex vivo CD3/CD28 stimulation.