IL-12 dependent/IFN gamma independent expression of CCR5 by myelin-reactive T cells correlates with encephalitogenicity.

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease with similarities to multiple sclerosis (MS). It is induced in mice by the transfer of myelin-reactive T cells. Here we demonstrate that IL-12 stimulates myelin-reactive T cells to up-regulate the beta-chemokine receptor, CCR5, in correlation with the acquisition of central nervous system-infiltrating and encephalitogenic properties.

Activation of APCs through CD40 or Toll-like receptor 9 overcomes tolerance and precipitates autoimmune disease.

Some autoreactive T cells normally escape thymic selection and persist in the periphery. This is true of myelin-reactive CD4(+) T cells, the effectors of experimental autoimmune encephalomyelitis (EAE) in laboratory animals and the presumed mediators of multiple sclerosis in humans. Nonetheless, most individuals do not succumb to autoimmune disease.