The observations made in RA may have interesting parallels with EGPA. Both RA and EGPA are autoimmune disorders and both are treated with standard immunosuppressive treatment including corticosteroids and immunosuppressants. In both diseases spontaneous and treatment-induced remission selleck compound using standard immunosuppression regimens are uncommon. Hence, in contrast to standard treatment, the case series presented herein suggest that immunomodulatory treatment of EGPA with IFN induces remission that may continue for several years. In fact, immunomodulatory therapy may be superior to standard immunosuppression

as it may induce long-term remission even after discontinuation of treatment. Little is known regarding maintenance of remission in EGPA treated with IFN. A small study with 13 patients reported a mean time to first relapse of 17 months [9]. In RA, almost half of the patients in whom maintained remission was achieved after discontinuation of therapy with DMARDs experienced check details a relapse during a 15-year follow-up period [14]. Thus, we cannot exclude that some, if not all, patients with EGPA in remission presented herein may also develop a relapse in the future. In RA, a proportion of patients with apparent clinical remission showed signs of progressive joint damage indicating subclinical disease activity [15]. This may be similar to the cases presented

above, which showed an increase in IgE serum levels and peripheral eosinophil counts whilst still being in clinical remission. In addition, there was no indication for organ

involvement including heart and lung. However, whether these biological parameters precede a relapse in EGPA remains unclear. IFN-treatment may cause significant adverse effects. All three patients experienced early side effects like arthralgia, myalgia and malaise and patient 3 also experienced depression after IFN-injections, but those side effects were transient. Patient 3 also developed hyperthyroidism, but was euthyroid under methimazole. Eventually, all patients had to discontinue IFN due to adverse events that disappeared shortly after discontinuation of treatment or did not progress ASK1 further (PNP of patient 1). Recent studies have shown that rituximab, a B-cell-depleting anti-CD20 monoclonal antibody and mepolizumab, an anti-IL-5-antibody also induce remission in EGPA [16], [17] and [18]. However, data on long-term efficacy in maintaining remission after discontinuation of treatment are not available making a reliable comparison of IFN-α to rituximab or mepolizumab impossible. We fully acknowledge the limitations of an observational study in only three patients. For instance, the patients presented were ANCA-negative. Thus, the beneficial effect of IFN may not apply to ANCA-positive cases. Previous reports [7] and [8] however have demonstrated that ANCA-positive patients equally respond to IFN-α. We also are aware that IFN may cause side effects. However, these adverse reactions were reversible.