[Successful treatment of interstitial pneumonitis with cyclosporin A in a patient with rheumatoid arthritis accompanied by acute interstitial nephritis].

A 49-year-old male was admitted to our hospital because of acute renal failure. He had been treated by a local doctor for rheumatoid arthritis (RA) during the past eight years. We treated him with steroid pulse therapy, because of suspected acute interstitial nephritis. We confirmed this diagnosis by renal biopsy and steroid pulse therapy markedly improved his renal dysfunction. Immunohistochemical studies revealed that interstitial infiltrating leukocytes consisted mainly of polymorphonuclear leukocytes (PMNs), macrophages and B lymphocytes, while T lymphocytes were less predominant. ELAM-1 and GMP-140 were expressed in the peritubular capillaries. These findings suggest that endothelial activation of the peritubular capillaries may cause interstitial infiltration of PMNs and macrophages, resulting in the development of acute interstitial nephritis. Four months later, he developed severe interstitial pneumonitis, and his symptoms were not improved by high-dose steroid pulse and cyclophosphamide pulse treatment. Eight weeks after the second admission, cyclosporin A (Cy A) was started. Three weeks after starting Cy A, he was free from symptoms and his chest radiograph was normalized. Renal function was also improved by Cy A. These observations suggest that endothelial activation by adhesion molecules may play an important role in RA-related autoimmune diseases and that Cy A might be efficacious in such cases.