slow bacterial infections

The idea that several 'idiopathic' or 'autoimmune' diseases are in fact caused by bacteria, probably related to the mycobacteria, which grow very slowly in the host, has been reported for some time. The diseases concerned are rheumatoid arthritis (RA), sarcoidosis, the inflammatory bowel diseases (Crohn's disease and ulcerative colitis), psoriasis, Takayasu's arteritis, and conceivably, 'giant cell arteritides', such as polymyalgia rheumatica. New data have increased the appeal of this hypothesis, and technical developments now make it accessible to investigation. The first section of this paper outlines the features of accepted slow bacterial infections, and points out the parallels with RA, inflammatory bowel disease, and sarcoidosis, including the presence of autoantibodies, agalactosyl IgG, and arthritis. The rest of the paper analyses these similarities in greater detail and reviews the evidence for two other crucial points: firstly, that there is altered responsiveness to mycobacteria in RA (and sarcoidosis); secondly, that mycobacteria can exist in forms which are difficult to detect by conventional histological techniques, and difficult to culture, but which are associated with the 'autoimmune' diseases considered here.