Fingerprinting of anti-citrullinated protein antibodies (ACPA): specificity, isotypes and subclasses.

Anti-citrullinated protein antibodies (ACPA) are a family of rheumatoid arthritis (RA)-specific autoantibodies that recognize the amino acid citrulline, resulting from the post-translational modification of arginine. Peptidyl arginine deiminase, the enzyme responsible for citrullination, is present in humans in different isoforms with different tissue distribution, enzymatic activity and target specificity; nonetheless, the number of proteins citrullinated in physiological or pathological conditions is wide, but not every citrullinated protein is a target for antibodies. In pre-RA patients the immune response to citrullinated antigens is initially restricted, expands with time and, after the onset of the disease, is relatively stable. ACPA are heterogeneous in terms of not only fine specificity but also isotype and IgG subclasses usage. This heterogeneity may be relevant for the immunopathogenesis of RA, conditioning the interaction of antibodies with complement and Fc receptors.

Long-term cyclic intravenous iloprost in systemic sclerosis: clinical experience from a single center.

The aim of the present study was to retrospectively evaluate response to therapy in 73 patients affected by systemic sclerosis (SSc) who underwent long-term cyclic treatment with intravenous iloprost for peripheral vascular involvement (average duration of treatment 54.12±41.04 months). Seventy-three SSc patients were enrolled. Data were collected by reviewing clinical records and by phone or direct interview. Patients underwent a thorough physical examination at the end of follow up. The incidence of severe vascular manifestations was also assessed. Statistical analysis was performed by Wilcoxon's signed rank test and descriptive statistics using Statview software. In this study cohort, 55 of 73 (75.2%) patients had a history of ischemic digital ulcers (DUs); 28 patients (38.4%) had active DUs at the beginning of treatment. Skin ulcers healed completely in 25 of 28 patients (89.3%) at the end of the first treatment. However, 40 of 55 patients (72.6%) relapsed after an average of 24 months. There was a significant correlation between relapse rate and/or number of ulcers and clinical factors (diffuse subset, changes in results of Allen's test, NT-pro BNP levels). The annual incidence of pulmonary arterial hypertension (PAH) was 2.34 (95%CI: 0.94-4.83) per 100 person years, the rate of gangrene was 2.7%, and no cases of scleroderma renal crisis were recorded. The incidence of PAH and of digital gangrene was higher than that observed in unselected SSc case series. These data suggest that our patients treated with iloprost have a higher vascular involvement than large case series of unselected SSc patients. A number of clinical factors are correlated to the severity of vascular involvement and could have an impact on the response to therapy. The clinical significance of these findings requires clarification and further investigation is needed.