The non-passage of mycobacteria from Freund's complete adjuvant granuloma depots to arthritic joints.

The intra-articular injection of antigen after immunization with that antigen in FCA, the mycobacterial component of which consisted of live M. avium or dead 125I-M. tuberculosis, resulted in identical chronic disease, experimental allergic arthritis. In the former case live mycobacteria could be isolated from the subcutaneous granuloma which developed at the injection site, and from arthritic joints into which 10 mug wet weight (equivalent of 2 mug dry weight) had been injected with this antigen. However, no mycobacteria could be isolated from other inflamed or normal joints. With 125I-labelled mycobacteria radioactive counting and radioautography clearly showed M. tuberculosis present in the subcutaneous granuloma but not in either injected or uninjected joints. The quantity of mycobacteria which could have been detected if present was estimated to be less than 1 mug dry weight. These results strongly suggest that mycobacteria do not travel from the granuloma depot to the arthritic joint, and that any mechanism one may consider to explain the chronicity of EAA cannot involve the physical presence of mycobacteria in the knee joint.