Salmonella-triggered Reactive Arthritis

We examined synovial-fluid cells from 15 patients with reactive arthritis after yersinia infection for the presence of yersinia antigens. Extensive bacterial cultures of the synovial fluid were negative. All the samples were studied by immunofluorescence with use of a rabbit antiserum to Yersinia enterocolitica O:3 and a monoclonal antibody to Y. enterocolitica O:3 lipopolysaccharide. Synovial-fluid cells from 41 patients with other rheumatic diseases served as controls. Synovial-fluid cells from 10 patients with reactive arthritis after yersinia infection stained positively on immunofluorescence; rabbit antiserum and the monoclonal antibody yielded similar results. In most patients the percentage of positive cells ranged from 1 to 10 percent, but in one patient nearly all the cells in the sample stained strongly. Most of the positively stained cells were polymorphonuclear leukocytes, but yersinia antigens were also found in mononuclear phagocytes. All the control samples were negative. Synovial-fluid cell deposits from nine patients were also studied by Western blotting with use of the same antibodies. The results were positive in six of the nine cell deposits from patients with reactive arthritis and in none of the 10 cell deposits from control patients with rheumatoid arthritis. We conclude that in patients with reactive arthritis after yersinia infection, microbial antigens can be found in synovial-fluid cells from the affected joints.

Synovial cells from nine patients with reactive arthritis following Salmonella enteritidis or Salmonella typhimurium infection were examined for salmonella antigens. Extensive bacterial cultures of the synovial fluid were negative. Eight synovial-fluid cell samples stained positively on immunofluorescence with rabbit antisera against heat-killed S enteritidis or S typhimurium or with monoclonal antibodies specific for the causative salmonella lipopolysaccharide (LPS). Synovial tissue from the ninth patient stained positively in the avidin-biotin-peroxidase complex method with the monoclonal antibody. Control samples (synovial-fluid cells from thirteen patients with other rheumatic diseases and synovial tissue from two) were negative. Synovial cells from eight patients and five controls were studied by western blotting with the same monoclonal antibodies. Four of the eight patients but no controls had blots indicating salmonella LPS in the synovial cells. The presence of bacterial LPS in the joint is a common and pathogenetically important feature of reactive arthritis.