Fibronectin gene expression in polymorphonuclear leukocytes. Accumulation of mRNA in inflammatory cells

Using a fibronectin cDNA probe, we have studied the accumulation of fibronectin mRNA in polymorphonuclear leukocytes (PMN) in response to inflammation. Nonactivated PMN from human peripheral blood were used as a source of noninflammatory cells and PMN from inflamed knee joints of patients with chronic inflammatory joint disorders (rheumatoid and psoriatic arthritis) were used as a source of inflammatory cells. By dot blot and Northern hybridization analysis, we have found the presence of fibronectin mRNA in these cells. Its size was estimated at approximately equal to 8.7-8.8 kilobases. When noninflammatory PMN were compared to inflammatory PMN in terms of fibronectin mRNA accumulation, a marked increase was found in inflammatory cells (2- to 12.7-fold stimulation). It was also observed that the increased mRNA levels in inflammatory PMN lead to increased synthesis of the protein. These findings establish that PMN are part of the fibronectin-producing cells and that the level of mRNA in these cells is influenced by the inflammatory process.