A B S T R A C T Cultures of dividing skin fibroblasts from normal and sclerodermatous human skin have permitted estimations of soluble collagen concentration, net collagen accumulation, cell-doubling times, and the comparison of morphologic and ultrastructural characteristics. In vitro, the scleroderma fibroblast produces more soluble collagen, synthesizes collagen more rapidly, and fourfold more of its protein synthetic activity is directed to collagen production than in the normal skin fibroblast. Cell-doubling times and morphologic and ultrastructural observations of cells in culture have not provided clues to the nature of the biologic defect in the regulation or activation of collagen synthesis by the scleroderma fibroblast.

Objective. To determine the frequency, clinical associations, and any major histocompatibility complex correlations of antifibrillarin antibodies in patients with systemic sclerosis (SSc).Methods. Antifibrillarin antibodies were determined by indirect immunofluorescence, immunoblotting, and immunoprecipitation, and HLA class I1 alleles by DNA oligotyping, in a large cohort of SSc patients.Results. Antifibrillarin was found in 8% of 335 SSc sera and was significantly more common in blacks (16%) than whites (S%), in males (33%) than females (14%), and in patients with cardiac, renal, or gut involvement. The HLA class I1 haplotype DRBZ *Z302, DQBZ*0604 was found significantly more frequently in SSc patients with antifibrillarin compared with racematched normal controls and 260 SSc patients without antifibrillarin. In addition, 1 or more of the HLA-DQB1

Endothelial injury, obliterative microvascular lesions, and increased vascular wall thickness are present in all involved organs in scleroderma. The vascular pathology is associated with altered vascular function with increased vasospasm, reduced vasodilatory capacity and increased adhesiveness of the blood vessels to platelets and lymphocytes. The extent of injury and dysfunction is reflected by changes in the circulating levels of vascular markers. The initial triggers for the vascular pathology are not known. Possible viral triggers are visited here, including cytomegalovirus in view of increased levels of anti-CMV antibodies in scleroderma, and the remarkable similarities between CMV vasculopathies and scleroderma vascular disease. Endothelial apoptosis in scleroderma may be related to viral infection, immune reactions to viral or environmental factors, reperfusion injury or to anti-endothelial antibodies. The impact of the vascular pathology on the evolution of tissue fibrosis is not known; still, cytokines (TGFbeta, IL4), vascular factors (endothelin), and growth factors (PDGF) are possibly crucial signals that link the vascular disease to tissue fibrosis. Knowledge of the regulation of these and other factors will provide the opportunity to develop more rational therapeutic approaches to the disease.

The prevalence of scleroderma spectrum disorders (including systemic sclerosis [SSc] meeting the American Rheumatism Association criteria and the less typical disorders meeting only our study criteria) was determined in a random sample of 6,998 subjects from the general population of South Carolina. The results suggest that the prevalence of these disorders may range from 67 to 265 per 100,000, which is 4.9 to 19.2 times higher than previously reported for definite SSc. The ratio of nondefinite cases to definite cases of SSc (those meeting American Rheumatism Association criteria) was 2.5. Most of the nondefinite cases were unrecognized prior to our study, which suggests the need for improved early diagnosis of scleroderma spectrum dis- orders. Brief histories of the 7 patients with scleroderma spectrum disorders whose cases formed the basis for our calculation of prevalence rates are included in this report.