Objective To evaluate the sites of expression of interleukin‐1β (IL‐1β), tumor necrosis factor α (TNFα), and inducible nitric oxide synthase (iNOS) in patients with inflammatory and degenerative joint diseases. Methods Cytokines and iNOS were detected by immunohistochemistry analysis of synovial and cartilage biopsy specimens obtained at knee arthroscopy in patients with rheumatoid arthritis (RA), psoriatic arthritis (PsA), osteoarthritis (OA), and traumatic knee arthritis. Cytokine and iNOS expression was quantified using computerized image analysis. Results IL‐1β, TNFα, and iNOS were highly expressed by synovial cells (lining layer cells, infiltrating leukocytes, endothelial cells) from patients with inflammatory arthritides and significantly less by synovial cells from patients with OA and traumatic arthritis. In contrast, the latter patients showed high chondrocyte expression of cytokines and iNOS while RA and PsA patients had only minor chondrocyte positivity. In both joint compartments, IL‐1β expression, TNFα expression, and iNOS expression were strongly correlated. Conclusion The enhanced and coordinated expression of IL‐1β, TNFα, and iNOS by chondrocytes strongly supports the hypothesis that chondrocytes are the major site of production of mediators of inflammation in human OA, thus playing a primary role in the pathogenesis of this disease.

Objective: To investigate the immunologic features of synovitis in patients with polymyalgia rheumatica (PMR) and to assess the modifications induced by corticosteroids.Methods. Arthroscopic biopsies of shoulder synovium were obtained from 12 patients with untreated PMR and from 7 patients with PMR that had been treated. Immunohistochemistry was performed on frozen sections utilizing a panel of monoclonal antibodies and computerized image analysis.Results. Synovitis was present in 10 of 12 (83%) untreated patients and in only 2 of 7 (29%) treated patients. The synovitis was characterized by vascular proliferation and leukocyte infiltration. Infiltrating cells consisted predominantly of macrophages and T Lymphocytes. Almost all T lymphocytes were CD45RO positive. A few neutrophils, but no B cells, natural killer cells, or y/S T cells were found. Intense expression of HLA class I1 antigens (DR moreso than DP moreso than DQ) was found in the lining layer cells as well as in macrophages and lymphocytes.

The sources of errors which may occur when cytophotometric analysis is performed with video microscopy using a charged-coupled device (CCD) camera and image analysis are reviewed. The importance of these errors in practice has been tested, and ways of minimizing or avoiding them are described. Many of these sources of error are known from scanning and integrating cytophotometry; they include the use of white instead of monochromatic light, the distribution error, glare, diffraction, shading distortion, and inadequate depth of field. Sources of errors specifically linked with video microscopy or image analysis are highlighted as well; these errors include blooming, limited dynamic range of grey levels, non-linear responses of the camera, contrast transfer, photon noise, dark current, read-out noise, fixed scene noise and spatial calibration. Glare, contrast transfer, fixed scene noise, depth of field and spatial calibration seem to be the most serious sources of errors when measurements are not carried out correctly. We include a table summarizing all the errors discussed in this review and procedures for avoiding them. It can be concluded that if accurate calibration steps are performed and proper guidelines followed, image cytometry can be applied safely for quantifying amounts of chromophore per cell or per unit volume of tissue in sections, even when relatively simple and inexpensive instrumentation is being used.

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The sources of errors which may occur when cytophotometric analysis is performed with video microscopy using a charged-coupled device (CCD) camera and image analysis are reviewed. The importance of these errors in practice has been tested, and ways of minimizing or avoiding them are described. Many of these sources of error are known from scanning and integrating cytophotometry; they include the use of white instead of monochromatic light, the distribution error, glare, diffraction, shading distortion, and inadequate depth of field. Sources of errors specifically linked with video microscopy or image analysis are highlighted as well; these errors include blooming, limited dynamic range of grey levels, non-linear responses of the camera, contrast transfer, photon noise, dark current, read-out noise, fixed scene noise and spatial calibration. Glare, contrast transfer, fixed scene noise, depth of field and spatial calibration seem to be the most serious sources of errors when measurements are not carried out correctly. We include a table summarizing all the errors discussed in this review and procedures for avoiding them. It can be concluded that if accurate calibration steps are performed and proper guidelines followed, image cytometry can be applied safely for quantifying amounts of chromophore per cell or per unit volume of tissue in sections, even when relatively simple and inexpensive instrumentation is being used.