SAT0403 Blood b cell subset profile disturbance in whipple’s disease

Background Technological advances have improved phenotypical characterisation of blood cells, and flow cytometry is currently used in haematology, infectious disease, systemic auto-immune diseases. Abnormalities of blood B cell subset profile might provide a useful diagnostic tool in systemic auto-immune diseases, especially for primary Sjogren’s Syndrome1 in which the activated B cells to memory B cells ratio is increased. Nevertheless, we observed that some patients suffering from chronic infection had lymphocytes disturbances similar to those observed in primary Sjogren’s Syndrome. Objectives Whipple’disease (WD) is a rare, systemic, disease caused by intracellular gram positive bacterium, Tropheryma Whipplei (TW). No previous study evaluated the role of B cells in WD. The aim of this study was to analyse whether the circulating blood B cell subset disturbances is characteristic of WD. Methods We collected characteristics of all patients coming for inflammatory rheumatism in our rheumatology department between April 2010 and December 2016. All of them had systematically routine examination, immunological tests, lymphocyte subsets in peripheral blood by flow cytometric analysis. We selected among this population those patients who also had PCR for TW for suspicion of WD, and compared the distribution of lymphocyte subsets of those with and without WD. Then, we evaluated their diagnostic value for WD using a ROC curve. Results Among 3494 patients with inflammatory rheumatism, 121 patients (212 visits) had a suspicion of WD and the diagnosis of WD was retained by an expert rheumatologist for 9 (7.4%) (22 visits). T cells and NK cells were not different whereas percentage of circulating memory B cells (IgD-CD38low) was lower (18.0%±9.7% vs 26.0±14.2%, p=0.041) and the ratio of activated B cells to memory B cells higher (4.4±2.0 vs 2.9±2.2, p=0.023), in patients compared with controls. More precisely, the analysis of the frequency of peripheral blood B cells showed that IgD +CD27 – naive B cells were higher (66.2%±18.2% vs 54.6±18.4%, p=0.047) and IgD-CD27 +switched memory B cells lower (13.3%±5.7% vs 21.4±11.9%, p=0.023), in patients compared with the controls. The best diagnostic value was obtained for the IgD +CD27- naive B cells (cut off 70.5, sensitivity 73%, specificity 80%). Conclusions Our study provides data on blood B cells disturbances and a first step towards understandings of immunological abnormalities in WD. These disturbances provide guidance for diagnosis and allow physiopathological hypothesis. Reference [1] Binard A, Le Pottier L, Devauchelle-Pensec V, Saraux A, Youinou P, Pers J-O. Is the blood B-cell subset profile diagnostic for Sjogren syndrome?Ann Rheum Dis2009;68(9):1447–52. Disclosure of Interest None declared