Interferon-γ Is Increased in Patients with Primary Sjogren's Syndrome and Raynaud's Phenomenon

ObjectivesTo determine the prevalence of Raynaud's phenomenon (RP) in patients with primary Sjogren's syndrome (pSS) and to identify clinical and immunological characteristics associated with this manifestation. Since increased interferon-γ (INF-γ) has been associated with RP, we also compared the INF-γ production in pSS patients with or without RP.MethodsRP was diagnosed if pSS patients presented with characteristic sequence of skin color changes of the digits. In uncertain cases noninvasive vascular tests were performed by ultrasound examination. The secretion of INF-γ by peripheral blood mononuclear cells was assessed by enzyme-linked immunospot analysis. Further, we examined the expression of different lymphocyte activation markers (CD25, CD45RO, CD69) on CD4+ T-cells by flow cytometric analysis.ResultsThirty-six of 108 patients with pSS had RP. In these patients we found a significantly increased number of INF-γ-secreting peripheral blood mononuclear cells compared with patients without RP or to healthy controls. Further, in patients with RP a significantly increased percentage of CD25-positive T-helper cells was detectable. In addition we found an association of leukopenia, thyroiditis, and lower C3 levels with RP in pSS patients.ConclusionsThese results suggest a pathogenic role of INF-γ in pSS patients with RP. Whether the RP is immune-mediated or whether INF-γ directly causes vasospasm still remains to be elucidated.