In the present study we have investigated the effects of immunosuppressive treatment on CD3+ (T-cell marker), CD244+ (CD28null T-cell marker) and FOXP3+ (regulatory T-cell marker) cells in myositis muscle tissue, and its relation to the short- and long-term clinical outcomes for patients with PM and DM, as well as the in vitro immunosuppressive effects on circulating CD28null T cells. The gene discussed is FOXP3; the disease is polymyositis.