Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


B-Cell Profiling Using Multi-Color Flow Cytometry as Biomarker of Disease Progression in Primary Sjogren's Syndrome (pSS).

Roberts2,  Mustimbo, Maguire3,  Craig, Rosenberg3,  Alex, Coca2,  Andreea, Anolik1,  Jennifer H., Sanz2,  Iñaki

University of Rochester, Rochester, NY
University of Rochester Medical Center, Rochester, NY
University of Rochester Medical Center

Purpose:

Current classification criteria for pSS are limited in their ability to conclusively diagnose patients with sub-clinical manifestations of disease. To remedy these limitations, we have initiated exploratory studies to identify candidate biomarkers for pSS. Multi-color flow cytometry was used cross-sectionally to identify a B-cell phenotypic signature of pSS and to determine if altered B-cell homeostasis in pSS is a predictive indicator of disease onset and/or progression. These signatures are currently being evaluated for their predictive value in an ongoing longitudinal analysis of patients with sicca symptoms, of no obvious clinical reason, that do not meet American European Consensus Group (AECG) criteria.

Methods:

B cells from pSS (n=20), sicca (n=14) and healthy (HC) patients (n=20) were analyzed by multicolor flow cytometry to identify differential memory and transitional B-cell subsets. Clinical parameters were used to examine the relationship of phenotypic abnormalities to disease status using Spearman Correlation. Complex, multidimensional immunological data were analyzed using reduction techniques including Principal Component Analysis (PCA).

Results:

We report decreased frequencies of switched (SM) (p<=0.0001) and unswitched (UM) (p<=0.0001) memory cells, and increased frequencies of IgD-CD27- switched B cells (p=0.03) and naïve B cells (p<=0.0001) in pSS compared to HC. Additionally, pSS patients exhibit increased frequencies of T1 and T2 transitional B cells compared to HC (p=0.005). The increased frequency of T1 and T2 cells correlated significantly with serum levels of BAFF, the main survival factor for transitional cells, which were significantly increased in pSS (p=0.05). Similar to pSS, sicca patients also feature decreased frequencies of SM (p=0.02) and UM (p=0.01) and increased frequencies of naïve B cells (p=0.02). Longitudinally, sicca patients with normal UM frequencies at baseline experience a dramatic permanent decline in frequency at 1 year and 2 years of follow-up that precedes a relative expansion in the CD27- memory and naive populations. Of note the decrease of UM cells correlated significantly with increased serum IgG, ESR, and years with sicca symptoms. Of great interest, UM decline preceded in some patients the presence of anti-Ro/La antibodies and decreased salivary function.

Discussion:

We have defined a B cell signature of pSS that allows for clustering/differentiation of Sicca patients that share a similar signature that clearly separates them from healthy controls and sicca patients that do not progress to pSS. Clinical parameters—elevated IgG, ESR and reduced C4 also cluster based on pSS B-cell signatures. The reduction of UM frequencies seem to be the first immunologic and permanent sign that Sicca patients may develop pSS. PCA of the complex multidimensional flow cytometric data identify the decrease in UM and increase in CD27- memory cells as the driving parameters of the B-cell signature in pSS. Further longitudinal examination of the pSS B-cell signature in Sicca patients will confirm the predictive value of peripheral blood multicolor flow cytometry as a diagnostic tool in pSS.

To cite this abstract, please use the following information:
Roberts, Mustimbo, Maguire, Craig, Rosenberg, Alex, Coca, Andreea, Anolik, Jennifer H., Sanz, Iñaki; B-Cell Profiling Using Multi-Color Flow Cytometry as Biomarker of Disease Progression in Primary Sjogren's Syndrome (pSS). [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1886
DOI: 10.1002/art.29651

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