Degeneration of optic axons induces the expression of major histocompatibility antigens.

Eye removal from adult rats causes induction of major histocompatibility complex (MHC) antigen expression by cells within areas of optic terminal degeneration. Class I MHC antigen expression occurs through the degenerating optic terminal areas, while class II MHC antigen expression is found within areas of degenerating myelinated axons. This could be an important step in the process of immunological recognition and subsequent rejection of neural transplants that are located in the region of the degenerating fibers. It could also be a precipitating factor in certain neurodegenerative diseases of the central nervous system.