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

To study innate immune responsiveness of HLA-B27 positive subjects recovered from Yersinia-triggered reactive arthritis (B27 + ReA+). Whole blood samples from 15 B27 + ReA+, 15 B27 + ReA- and 15 B27 - ReA- subjects were heparinized, aliquoted and (i) kept at 0 degree 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 degrees 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. 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 microg/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. Enhanced neutrophil reactivity observed may exacerbate innate immune inflammation in HLA-B27 positive ReA patients.