Decreased recent thymus emigrant number in rheumatoid factor-negative polyarticular juvenile idiopathic arthritis

CER295
2010 Vol.28, N°3
PI 0348, PF 0353
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PMID: 20460033 [PubMed]

Received: 19/03/2009
Accepted : 17/12/2009
In Press: 23/06/2010
Published: 23/06/2010

Abstract

OBJECTIVES:
To determine TCR excision circle (TREC) levels, a marker of recent thymic emigrants, in the peripheral lymphocyte pool of rheumatoid factor-negative (RF∅) polyarticular juvenile idiopathic arthritis (JIA) children.
METHODS:
We studied TREC levels in peripheral blood mononuclear cells (PBMC) in 30 RF∅ polyarticular JIA children with active disease and in 30 age- and gender-matched healthy controls. Signal-joint TREC concentration was determined by real-time quantitative-PCR as the number of TREC copies/μg PBMC DNA gauged by a standard curve with known number of TREC-containing plasmids.
RESULTS:
TREC levels in PBMC were significantly lower in JIA (4.90 ± 3.86 x 104 TRECs/μg DNA) as compared to controls (10.45 ± 8.45 x 104 TRECs/μg DNA, p=0.001). There was an inverse correlation between age and TREC levels in healthy children (r=-0.438, p=0.016) but not in JIA. No clinical association was observed between TREC levels and disease activity and use of oral steroids and methotrexate.
CONCLUSIONS:
The finding of decreased PBMC TREC levels in RF∅ polyarticular JIA children is consistent with a low proportion of recent thymus emigrants. This may interfere with the equilibrium between populations of polyclonal and naïve T cells versus oligoclonal memory auto-reactive T cells and, therefore, may hinder the maintenance of immune tolerance in this disease.