CD28 and polymyositis: Plasmacytoid DCs circulating display an unformed phenotype featured with low CD86 expression, while myeloid DCs notably rise throughout chronic infection.[31] Muscle infiltrates in polymyositis patients are mostly CD28null T cells,[32] which exhibit cytotoxicity to autologous muscle cells.[33] Additionally, the increase of CD8+ CD28 circulating T cells is characteristic of systemic inflammation in myositic dermatomyositis.[34]