Clinical Phenotype and Mechanisms of Leukopenia/Neutropenia in Patients with Primary Sjögren's Syndrome.

Sjögren's syndrome (SS) is a chronic, systemic autoimmune disease which afflicts mainly the exocrine salivary and lachrymal glands, leading to mouth and eye dryness. However, any organ can be affected during the disease course, resulting in a variety of clinical manifestations. Sjögren's syndrome clinical manifestations can be classified into glandular (sicca manifestations or parotid swelling), extra-glandular, either nonspecific (arthralgias, arthritis, Raynaud's phenomenon, fatigue) or peri-epithelial (primary biliary cirrhosis, interstitial nephritis, bronchiolitis), and extra-epithelial (palpable glomerulonephritis, peripheral neuropathy, purpura). In addition, SS patients display high risk for B cell lymphomas due to chronic antigenic stimulation. Although disease pathogenesis remains unclear, genetic, environmental, and immunologic factors are implicated. In the context of systemic autoimmune manifestations, SS patients may also present with hematologic abnormalities including anaemia, leukopenia (mainly neutropenia or lymphopenia), and thrombocytopenia. Although leukopenia has been reported as a laboratory finding in many case series or cohorts of SS patients and in very few studies it has been proposed as an independent risk factor for lymphoma, the clinical phenotype of SS patients with leukopenia/neutropenia and the implicated pathogenetic mechanisms have not been elucidated. In the current study, we intend to analyse the clinical phenotype of leukopenic/neutropenic SS patients and explore the possible pathogenetic mechanisms by detecting anti-neutrophil antibodies and investigate the role of apoptotic pathways, especially the contribution of TRAIL pathway and the cFLIP molecule.