The role of CD8+ T cells in multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) is still unclear. We describe here significantly reduced disease activity of EAE both in Lewis rats depleted of CD8+ T cells by monoclonal antibodies and CD8 knockout rats, which was accompanied by reduced leucocyte infiltration into the spinal cord. We detected myelin basic protein (MBP)-specific CD4+ T cells in peripheral lymphoid organs of CD8-depleted animals which, however, failed to differentiate into interferon-γ-producing effector cells. Our results indicate that CD8+ T cells interact with myelin-specific CD4+ T cells early in EAE enabling them to differentiate into pathogenic effector cells.
The role of CD8 T cells may be unclear in MS, are they anti-viral?
After years of studies in EAE documenting that blockade of CD8 positive T cells either does nothing or augments EAE, now we find it inhibits EAE.
It is suggested that the CD8 cells help the CD4 cells to become damaging cells. I wonder if this has anything to do with the likelihood that rat macrophages can express CD8!