Studies on fibronectin in inflammatory vs non-inflammatory polymorphonuclear leucocytes of patients with rheumatoid arthritis. I. Immunofluorescent and flow cytometric analysis.

Using indirect immunofluorescence and flow cytometry, we studied the reactivity of an antibody to human fibronectin with human polymorphonuclear leucocytes (PMNL). Our main objective was to compare the intensity of reaction of this antibody with inflammatory vs non-inflammatory PMNL. We used peripheral blood PMNL as a source of non-inflammatory cells and PMNL isolated from the synovial fluid of patients with rheumatoid arthritis as a source of inflammatory cells. Our findings revealed considerably brighter staining of the inflammatory PMNL. Using flow cytometry as a method of measurement, a difference in fluorescence intensity of at least 40 channels (log scale) was observed in all 12 patients studied when comparing peripheral blood with synovial fluid PMNL. In inflammatory PMNL, fibronectin was found both at the intracellular and membrane levels of the cell whereas fibronectin could be detected only intracellularly in non-inflammatory PMNL.