Resolution of Cutaneous Lesions of Granuloma Annulare by Intralesional Injection of Human Fibroblast Interferon

To the Editor.—  We report a successful clinical trial of interferon beta-1 for the treatment of granuloma annulare. Although the cause of granuloma annulare still remains unknown, by histochemical and electron microscopic studies, Umbert and Winkelmann¹ have observed activated macrophages in the lesion and have presumed that activation of mononuclear phagocytes may be the central event in an inflammatory process of granuloma annulare. Lee and Epstein² report that interferon beta inhibits maturation of monocytes to macrophages, and we found that interferon beta inhibited activation of monocytes.³ These findings prompted us to study the effect of interferon beta on granuloma annulare.Human interferon beta-1 was a product of human fibroblasts stimulated with Poly I:C.Since human serum albumin was added, as a stabilizer, into a vial of interferon beta-1, a placebo vial, which contained only the same amount of human serum albumin, was also prepared (Toray Industries, Tokyo). A vial of interferon beta-1 was