Characterization of a spontaneous disease of white leghorn chickens resembling progressive systemic sclerosis (scleroderma)

University of California, Davis (UCD) line 200 White Leghorn Chickens spontaneously develop a syndrome that has many analogous features to human progressive systemic sclerosis. This syndrome is characterized by progressive involution of comb, dermal fibrosis, and distal polyarthritis. These three features occur within 6 wk after hatching, and are accompanied by a 40% mortality as a result of vaso-occlusive disease, with development of secondary infection of peripheral gangrenous lesions. Birds that survive greater than 2 mo after hatching progressively develop fibrosis of the esophagous and mononuclear infiltration of heart and kidney, with prominent occlusion of small and medium sized blood vessels. In addition, line 200 chickens develop rheumatoid factors, antinuclear antibodies, and antibodies to collagen, but do not have antibodies to thymocytes, DNA, or extractable nuclear antigens. Moreover, antinuclear antibodies when studied using HEp-2 cells as substrate demonstrate predominantly a speckled pattern. This syndrome of line 200 chickens is not detectable in F1 crosses to several UCD inbred lines. F1 X parental line BC1 backcrosses have an approximately 50% incidence of disease, suggesting that this syndrome is inherited as autosomal recessive. However, only 4% of F2 generation birds show abnormal symptoms, suggesting the presence of modifying genes. There is no appearance of IgG deposition, as determined by immunofluorescence, in either skin, blood vessels, esophagus, or heart. However, approximately 20% of chickens have a glomerulonephritis; this feature appears to be a terminal event and does not appear clinically significant. Although this syndrome of line 200 chickens has several features that are in sharp distinction to human scleroderma, the presence of common immunologic and pathologic denominators suggest that this spontaneous disease may be an appropriate model to develop a better understanding of autoimmune connective tissue diseases.