Autoantibodies against B23, a nucleolar phosphoprotein, occur in scleroderma and are associated with pulmonary hypertension

Objective. To determine whether the abundant nucleolar phosphoprotein B23 is a target of autoantibodies in scleroderma, and to examine the clinical phenotype associated with these antibodies. Methods. Ninety-two randomly selected scleroderma sera were screened by enzyme-linked immunosorbent assay against recombinant human B23. Demographic, clinical, and serologic parameters associated with B23 autoantibody status were examined. Results. We demonstrated that autoantibodies against B23 occur in ∼11% of sera obtained from patients with scleroderma. B23 seropositivity was related to pulmonary hypertension, antifibrillarin antibody, anti-RNP antibody, and decreased lung capacity. In multivariate analysis, B23 autoantibodies remained strongly associated with moderate-to-severe pulmonary hypertension and antifibrillarin antibodies. Conclusion. These data unite B23 with the group of nucleolar autoantigens targeted in scleroderma and thus focus attention on changes in the nucleolus that render its components immunogenic in this disease. The demonstration that antibodies to B23 are associated with an increased prevalence of pulmonary hypertension points to anti-B23 antibodies as a possible marker of a specific phenotype in scleroderma.