ANCA induces 2 integrin and CXC chemokine-dependent neutrophil-endothelial cell interactions that mimic those of highly cytokine-activated endothelium

Antineutrophil cytoplasm antibodies (ANCA) activate neutrophils to undergo a series of coordinated interactions, leading to transendothelial migration, eventually culminating in vascular destruction. The molecular events underlying neutrophil recruitment in ANCA-associated vasculitis need to be defined to enable effective therapeutic manipulation. A flow-based adhesion assay was used to investigate the role of 2 integrins (CD11a/ CD18 and CD11b/CD18) and chemokines receptors [CXC chemokine receptor (CXCR)1 and CXCR2] in neutrophil migration through the endothelium. Two endothelial models were used: a highly activated model stimulated with 100 U/ml tumor necrosis factor (TNF) and a minimally activated model stimulated with 2 U/ml TNFand in which ANCA was present as a secondary neutrophil stimulus. CD11a/CD18, CD11b/CD18, and CXCR2 contributed to adhesion and transendothelial migration in both models. However, when the endothelium was minimally activated with TNF, CD11b/CD18 played an important role in stabilizing adhesion induced by ANCA immunoglobulin G (IgG). Analysis of 2 integrins and chemokines receptors demonstrated that ANCA IgG had no effect on expression levels at the neutrophil surface but enabled an active conformational change of CD11b/ CD18. Similar molecular mechanisms control neutrophil adhesion and migration through highly or minimally TNF-activated endothelium. However, the direct ANCA-mediated neutrophil stimulation is needed to drive migration through minimally activated endothelium, and CD11b/CD18 is recruited for greater stability of adhesion during this process and can undergo an activatory, conformational change in response to ANCA IgG. J. Leukoc. Biol. 76: 000–000; 2005.