RESEARCH - Decreased BAFF-R associated with increased disease activity in primary Sjögren's syndrome and SLE

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Ann Rheum Dis. Published Online First: 21 December 2006.

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Extended Report

Decreased BAFF-R on peripheral lymphocytes associated with increased disease

activity in primary Sjögren's syndrome and systemic lupus erythematosus

Jérémie Sellam 1, Corinne Miceli- 1, Jacques Gottenberg 1, Marc

Ittah 1, Frédéric Lavie 1, Lacabaratz 1, Nicolas Gestermann 1,

is Proust 1, Olivier Lambotte 1 and Xavier Mariette 1*

1 Bicêtre Hospital, INSERM U802, France

Abstract

Objective:To analyse B-cell activating factor (BAFF) receptor (BAFF-R) on

peripheral lymphocytes from patients with primary Sjögren's syndrome (pSS)

and systemic lupus erythematosus (SLE).

Patients and methods:Peripheral blood mononuclear cells from 20 pSS, 19 SLE

patients and 15 controls were examined by flow cytometry to investigate

BAFF-R mean fluorescence intensity (MFI) on lymphocytes. BAFF-R mRNA level

from isolated blood B cells of 9 pSS patients and 8 controls was assessed by

real-time quantitative RT- PCR. BAFF serum level was determined by ELISA.

Results:In all subjects, BAFF-R was expressed on all naïve CD27- and memory

CD27+ B cells and was present on <0.5% of T cells. BAFF-R expression on B

cells was significantly decreased in pSS patients as compared with controls

(MFI=7.8 vs 10.6, p=0.001) and was intermediate in SLE patients (MFI=9.5).

Serum BAFF level was inversely correlated with BAFF-R MFI (p=0.007) but not

because of competition between endogenous BAFF (at observed concentrations

in patients) and the monoclonal antibody (11C1) detecting BAFF-R. BAFF-R

mRNA level did not differ between pSS patients and controls (p=0.48). BAFF-R

MFI decreased after overnight culture with rhBAFF (from 32.5 to 25.4,

p=0.03). Contrary to serum BAFF level, BAFF-R expression was correlated with

extraglandular involvement in pSS and SLE Disease Activity Index.

ConclusionsBAFF-R expression is reduced on peripheral B cells of pSS and SLE

patients. This downregulation occurs through a post-transcriptional

mechanism and could be the consequence of chronic BAFF increase. BAFF-R

level on B eclls could be a novel activity bio-marker in autoimmune

diseases.

http://ard.bmj.com/cgi/content/abstract/ard.2006.065656v1?papetoc

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