IL-10 is involved in the suppression of experimental autoimmune encephalomyelitis by CD25 super(+)CD4 super(+) regulatory T cells

CD25 super(+)CD4 super(+) regulatory T cells inhibit the activation of autoreactive T cells in vitro and in vivo, and suppress organ-specific autoimmune diseases. The mechanism of CD25 super(+)CD4 super(+) T cells in the regulation of experimental autoimmune encephalomyelitis (EAE) is poorly understood. To assess the role of CD25 super(+)CD4 super(+) T cells in EAE, SJL mice were immunized with myelin proteolipid protein (PLP) sub(139-151) to develop EAE and were treated with anti- CD25 mAb. Treatment with anti-CD25 antibody following immunization resulted in a significant enhancement of EAE disease severity and mortality. There was increased inflammation in the central nervous system (CNS) of anti-CD25 mAb- treated mice. Anti-CD25 antibody treatment caused a decrease in the percentage of CD25 super(+)CD4 super(+) T cells in blood, peripheral lymph node (LN) and spleen associated with increased production of IFN- gamma and a decrease in IL-10 production by LN cells stimulated with PLP sub(130-151) in vitro. In addition, transfer of CD25 super(+)CD4 super(+) regulatory T cells from naive SJL mice decreased the severity of active EAE. In vitro, anti-CD3-stimulated CD25 super(+)CD4 super(+) T cells from naive SJL mice secreted IL-10 and IL-10 soluble receptor (sR) partially reversed the in vitro suppressive activity of CD25 super(+)CD4 super(+) T cells. CD25 super(+)CD4 super(+) T cells from IL-10-deficient mice were unable to suppress active EAE. These findings demonstrate that CD25 super(+)CD4 super(+) T cells suppress pathogenic autoreactive T cells in actively induced EAE and suggest they may play an important natural regulatory function in controlling CNS autoimmune disease through a mechanism that involves IL-10.