Neutrophil Adhesion Molecule Expression in Familial Mediterranean Fever: Discordance between the Intravascular Regulation of β₂ Integrin and L-Selectin Expression in Acute Attack

Background: To determine the surface expression of neutrophil β ₂ integrin (CD11b/CD18) and L-selectin (LS) adhesion molecules in patients with familial Mediterranean fever (FMF) and to investigate the in vitro regulation of their expression in response to chemoattractant stimuli. Methods: Neutrophil surface expression of CD11b and LS molecules was analyzed by flow cytometry in anticoagulated whole blood drawn from FMF patients and normal controls, and the in vitro regulation of these molecules induced by the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (FMLP) was assayed. Results: Patients during acute FMF attacks showed a statistically significant increased neutrophil surface CD11b compared with normal controls (mean fluorescence intensity: 22.8 ± 13.7 vs 12.8 ± 10.41, respectively; p = .03). There was no difference in LS expression between the groups. Neutrophils of FMF patients regulate CD11b and LS expression induced by chemoattractant (FMLP) stimulation to a degree similar to that in controls. Conclusions: β₂ Integrin is up-regulated during an acute attack of FMF in dissociation with LS expression, suggesting a unique nonchemoattractant-mediated neutrophil activation.