Cellular immune responses to microbial antigens have been implicated in the pathogenesis of some forms of arthritis including reactive arthritis, Reiter's syndrome, ankylosing spondylitis and rheumatoid arthritis. We investigated the proliferative T cell responses of paired peripheral blood (PB) and synovial fluid (SF) mononuclear cells (MC) to so-called arthritogenic bacteria (Yersinia enterocolitica and Salmonella typhimurium), to control antigens, such as Candida albicans, mumps virus and purified protein derivative, to the recombinant mycobacterial 65-kDa heat-shock protein (hsp 65) and the mitogen phytohemagglutinin (PHA) in 16 patients with different inflammatory rheumatic diseases. The [3H]thymidine uptake of unstimulated cells (medium control) as well as the proliferative response to the different antigens tested was markedly increased in SFMC irrespective of the underlying rheumatic disease. In contrast, mitogenic stimulation was decreased in SFMC. The proliferative response to the hsp 65 correlated significantly with the responses to Yersinia, Salmonella and Candida. These results may reflect an enhanced function of SF antigen-presenting cells, different functional properties and subset distributions of PB and SF T cells with a preferential accumulation of helper-inducer/memory T cells or a maintenance of an ongoing immune response by T cells cross-recognizing self epitopes such as epitopes located on the hsp 65. Thus, care should be taken in the interpretation of SF T cell responses to microbial antigens as diagnostic tools in arthritis.

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The correlation between arthroscopic observations and histologic changes in rheumatoid arthritis is still controversial. Synovial samples of 21 knee joints in rheumatoid arthritis patients were comparatively investigated by endoscopy and histology. Biopsies were scored by an endoscopist and subsequently dissected. Different histochemical and immunocytochemical staining techniques were used to define inflammatory activity. Arthroscopic and histological values were compared by rating scales and variance analysis. Our study indicates that synovial biopsy is of diagnostic value in rheumatoid arthritis. However, its usefulness depends on the histochemical methods used. The results revealed highly significant correlations of endoscopic features with the number of neutrophilic granulocytes, intravascular leukocytes, and peroxidase-positive macrophages. However, no relationship was found between the detection of lymphocytes or resident macrophages and inflammatory scores. The close correlation between endoscopic and histological findings suggests that arthroscopic evaluation allows a valuable classification of the inflammatory activity in rheumatoid synovitis.

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The radiation exposure during biomechanical investigation of the shoulder joint done with a digital radiography system (Polytron 1000 VR - Siemens) was measured experimentally. Total radiation dose and surface dose were determined by phantom measurements. The radiation exposure per image is about 1/6 to 1/7 of that of a conventional study. The digital radiography system used is thus suitable for kinesiologic studies of large joints in healthy volunteers.