The Turkish Journal of Pediatrics 2010 , Vol 52 , Num 1
Toll-like receptors 2 and 4 cell surface expression reflects endotoxin tolerance in Henoch-Schönlein purpura
1Department of Basic Oncology, Institute of Oncology, and 2Pediatric Nephrology Unit, Department of Pediatrics, Hacettepe University Faculty of Medicine, Ankara, Turkey We aimed to analyze the Toll-like receptor (TLR)2 and TLR4 expressions, which are known to be involved in the recognition of pathogens by the innate immune system, in patients with Henoch-Schonlein purpura.

Twenty-three patients (10 males, 13 females, aged 4-16 years) with a clinical diagnosis of Henoch-Schonlein purpura were enrolled. Twenty healthy agematched children (10 males, 10 females) served as controls. TLR2 and TLR4 expression levels on peripheral blood mononuclear cells (PBMCs) were determined by flow cytometric analysis. PBMCs were cultured with heat shock protein (HSP) 60 (1 ƒÊg/ml) as an endogenous ligand for TLR.

Levels of TLR2 and TLR4 expression on PBMC were significantly lower in the Henoch- Schonlein purpura patients compared to healthy controls when stimulated with HSP60 and with lipopolysaccharide (LPS) (p<0.05 for both). There was no significant difference between the stimulated and unstimulated samples from the patients.

The lower TLR response to these ligands among these patients may reflect a tolerance to bacterial antigens. Further studies will clarify whether tolerance to microbial antigens may have a role in the pathogenesis and course of Henoch-Schonlein purpura Keywords : Henoch-Schönlein purpura, endotoxin tolerance, heat shock protein 60, Toll-like receptor 2, Toll-like receptor 4.

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