Persistence of antigen in rabbit synovial membrane

Abstract

It is already known that rabbits which show delayed-type hypersensitivity to an antigen will, after a single injection of the same antigen into a knee joint develop a chronic proliferative synovitis. It is also known that almost all of a foreign protein injected into a normal knee joint is rapidly cleared in a few days.

It has now been shown that if an animal is given foreign protein into a knee joint, and delayed-type hypersensitivity is produced later, that a chronic proliferative synovitis can also develop. This suggests that minute amounts of foreign protein can persist in an antigenic form in normal rabbit synovial membrane. It is possible that the persistence of this small amount of antigen may account in part for the chronicity of this form of experimental synovitis, and the fact that unlike human rheumatoid arthritis this type of experimental synovitis is confined to the joint injected with antigen.