Major histocompatibility complex molecules on parenchymal cells of the target organ protect against autoimmune disease.

Parenchymal cells of the autoimmune organ may only express major histocompatibility complex (MHC) molecules during the disease process. In this paper, we hypothesize that the appearance of MHC molecules on parenchymal cells may augment the activation of invading autoreactive T cells and either exacerbate or suppress local inflammation. It is speculated that like many biological responses this is a two-edge sword - namely, the expression of modest levels of MHC molecules may inhibit the activation of invading T cells, whereas overexpression of these molecules may promote activation of autoimmune T cells, enhancing the inflammatory cascade, thus leading to tissue damage.