Establishment and characterization of a human B cell line from the lung tissue of a patient with scleroderma; Extraordinary high level of IL-6 secretion by stimulated fibroblasts

Progressive systemic sclerosis is a connective tissue disease of unknown ae tiology. This is the first study to demonstrate induction by a human B cell line of IL-6 secretion from fibroblasts. The cell line was established fro m lesional lung tissue of a patient with progressive systemic sclerosis. Th ese cells, referred to as kon-1 cells, showed characteristics of pro-B cell by flow cytometry. Although kon-1 cells alone secreted a small amount of I L-6, a co-culture of kon-1 cells with normal lung fibroblasts significantly increased IL-6 levels. Whereas IL-6 mRNA was weakly expressed in kon-1 cel ls alone, it was clearly expressed in cells from the co-culture. Immunocyto chemical identification of IL-6 showed localization in the cytoplasm of fib roblasts. IL-6 is a pleiotropic cytokine, essential for B cell differentiat ion, which has been shown to stimulate the production of collagen and glyco saminoglycan. Thus, abnormally augmented B cell proliferation and the infla mmatory response stimulated by these cells may cause the fibrotic changes i n patients with progressive systemic sclerosis. A 2001 Academic Press.