Background/Purpose: Whipple’s disease (WD) is a rare, systemic, disease caused by the intracellular Gram-positive bacterium Tropheryma whipplei (TW). This ubiquitous commensal organism is transmitted among humans via the oro-fecal route. Chronic WD and the immune system are closely linked. To our knowledge, no studies have evaluated the potential role for B cells in WD. We noticed lymphocyte subset abnormalities similar to those seen in primary Sjögren’s syndrome in patients whose symptoms suggested ankylosing spondyloarthritis (inflammatory low back pain) or rheumatoid arthritis (chronic polyarthritis). We then observed the same abnormalities in patients with infectious rheumatic diseases due in particular to bartonella (cat-scratch disease) or TW. We therefore designed the present study with the aim of describing peripheral-blood lymphocyte subsets, with special attention to B cells, in patients with WD. We aimed to assess whether any abnormalities found were sufficiently characteristic to help in diagnosing and monitoring WD.

Methods:

Consecutive patients seen between 2010 and 2016 for suspected inflammatory joint disease were identified retrospectively. Results of standardized immunological and serological tests and of peripheral-blood B-cell and T-cell subset analysis by flow cytometry were collected. Patients with criteria suggesting WD underwent PCR testing for Tropheryma whipplei, and those with diagnosis of WD (cases) were compared to those without diagnosis (controls). We used ROC curve analysis to evaluate the diagnostic value of flow cytometry findings for WD.

Results:

Among 2917 patients seen for suspected inflammatory joint disease, 121 had suspected WD, including 9 (9/121, 7.4%) with a positive PCR and a dramatic response to antibiotic therapy for WD. Proportions of T cells and NK cells were similar between cases and controls, whereas cases had a lower proportion of circulating memory B cells (IgD^–CD38low, 18.0%±9.7% vs. 26.0%±14.2%, P=0.041) and higher ratio of activated B cells over memory B cells (4.4±2.0 vs. 2.9±2.2, P=0.023). Among peripheral-blood B-cells, the proportion of IgD+CD27- naive B cells was higher (66.2%±18.2% vs. 54.6%±18.4%, P=0.047) and that of IgD-CD27+ switched memory B cells lower (13.3%±5.7% vs. 21.4%±11.9%, P=0.023), in cases vs. controls. The criterion with the best diagnostic performance was a proportion of IgD+CD27- naive B cells above 70.5 %, which had 73% sensitivity and 80% specificity.

Conclusion:

Our study provides data on peripheral-blood B-cell disturbances that may have implications for the diagnosis and pathogenetic understanding of WD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/peripheral-blood-b-cell-subset-disturbances-in-whipples-disease/