OP0035 Circulating Plasmablasts Levels Reflect Inflammatory Activity in IGG4-Related Disease Lesions as Assessed by Quantitative Positron Emission Tomography

BackgroundIgG4-Related Disease (IgG4-RD) is a systemic inflammatory condition characterized by fibrous swelling of affected organs, serum IgG4 elevation, and IgG4+ plasmacells tissue infiltration. 18-Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan is emerging as a promising imaging technique to detect organs involved by IgG4-RD and to assess disease response to treatment. The relationship between FGD-PET findings and immunological perturbations occurring in IgG4-RD has never been evaluated.ObjectivesTo correlate the intensity and distribution of FDG-PET uptake with clinical and immunological parameters in patients with active untreated IgG4-RD.MethodsPatients with active, untreated, biopsy proven IgG4-RD were included in the study. Disease activity was assessed through clinical (IgG4-RD Responder Index (RI)) and immunological (erythrocyte sedimentation rate (ESR), C reactive protein (CRP), serum IgG4, and circulating plasmablasts) parameters. Plasmablasts, a recently characterized disease biomarker, were identified as CD19+CD20-CD27+CD38bright cells on flow cytometry. FDG-PET/CT was performed in all patients at diagnosis. Quantitative assessment of FDG uptake was measured using the mean Standardized Uptake Value corrected for the Partial Volume Effect (PVC-SUV). Lymph nodes