title: P6-005　　Plasmacytoid dendritic cells and mast cells associated with sialadenitis in primary Sjören's syndrome.
abstract: To study the precise role of Plasmacytoid dendritic cells (PDCs) and mast cells (MC) in Sjögren's Syndrome (SS). Lip specimen (178 SS vs 7 Sicca) were performed on lymphocytes infiltration, acinar atrophy and intralobular fibrosis. MC, PDCs, CD68 and CXCL13 were detected by IHC or toluidine blue. CXCL13 gene was detected by PCR. Significant lymphocytes infiltration, acinar atrophy and intralobular fibrosis were observed in SS. PDCs and MC were increased in SS than Sicca (p=0.03/0.02). Positive correlation between PDCs with lymphocytes infiltration (p=0.02) and MC with intralobular fibrosis (p=0.03) in primary SS (pSS) was observed. Within the pSS, PDCs correlated with CXCL13+cells, especially CXCL13+macrophages. When macrophages were stimulated with IFN-a in vitro, CXCL13 gene was up-regulated.Our data suggests the specific role of PDCs in lymphocyte infiltration and MCs in intralobular fibrosis of pSS. Therefore, it is likely that PDCs in early stage inducing CXCL13 production from macrophages due to IFN-a contributing to lymphocyte infiltration further constructing germinal centers. In addition, MC seems to be involved in intralobular fibrosis which occurs in mid to late stage of SS.