Neutrophils of healthy subjects with a history of reactive arthritis show enhanced responsiveness, as defined by CD11b expression in adherent and non-adherent whole blood cultures

Abstract

Objectives. To study innate immune responsiveness of HLA-B27 positive subjects recovered from Yersinia-triggered reactive arthritis (B27 + ReA+). Methods. Whole blood samples from 15 B27+ReA+, 15 B27+ReA- and 15 B27 - ReA-subjects were heparinized, aliquoted and (i) kept at 0°C to preserve constitutive cell surface marker status, or (ii) cultured with or without bacterial lipopolysaccharide (LPS) supplement, in adherent and non-adherent conditions at 37°C for 4 h. Neutrophil surface expression of CD11b, CD14 and CD16 was quantified flow cytometrically, and compared between the subject groups using Jonckheere-Terpstra test. Results. The B27+ReA+group showed significantly higher CD11b levels than the B27 - ReA - group on non-adherent neutrophils cultured with LPS as 100 pg/ml (P=0.027), 10 ng/ml (P=0.048) or 1 μg/ml (P=0.024), or on adherent neutrophils without LPS supplement (P=0.040). CD14 and CD16 expression on cultured neutrophils and constitutive expression of all three markers were comparable between the groups. Conclusions. Enhanced neutrophil reactivity observed may exacerbate innate immune inflammation in HLA-B27 positive ReA patients. © The Author 2007. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved.