IS GRAFT-VERSUS-HOST DISEASE A RELIABLE MODEL FOR SCLERODERMA? YOSEPH A. MEKORI ~:', HENRY N. CLAMAN Dwision of Allergy and Clinical Immunology, Departments of Medicine and of Microbiology~Immunology, University of Colorado School of Medicine, Denver Scleroderma or progressive systemicsclerosis (PSS)is a disease of unknown etiology characterized by abnormally increased collagen deposition in the skin associated with a cellular infiltrate consisting primarily of T lymphocytes. The course is usually slowly progressive and chronically disabling, but it can be rapidly progressive and fatal because of involvement of internal organs 1°,22. Scleroderma has many dinical features in common with other rheumatic diseases, such as systemic lupus erythematosus, dermatomyositis and rheu- matoid arthritis'8. The association of this disease with Sj6gren's syndrome and the serologic abnormalities seen in the majority of cases (e.g. the presence of antinuclear antibodies, rheumatoid factor, hypergammaglobulinemia) are suggestive of an immunologic aberration in these patients 2°. Unfortunately, research on the pathogenesis of PSS is severely hampered by the absence of an animal model. Recently, two animal models have been proposed as suitable for the study of scleroderma. One is an inherited fibrotic disease of white leghorn chickens exhibiting spontaneously occurring disease with visceral as well as cutaneous and serologic abnormalities ~.29.However, there are major differences clinically and pathologically between this syndrome and human PSS =3,=9. The animal disease is significantly more fulminant, and the skin lesions, although exhibiting dermal fibrosis and increased collagen, have a more intense cellular infiltrate than usually seen in PSS. Also, the vascuIar lesion is characterized by muscular hypertrophy rather than intimal proliferation and these birds often develop Key-words: Chronicfibrosis; Graft-versus-host disease; Immunological abnormalities; Rheumatic diseases; SderodermcL Presently in: Allergy~Immunology Unit, Meir Hospital and the Department of Medicine, Sackler School of Medicine, Tel-Aviv University, Kfar-Saba, 44281 Israel. Accepted for publication on July 29, 1986. La Ricerca Clin. Lab. 16, 509, 1986. 509