Eosinophil major basic protein enhances the expression of neutrophil CR3 and p150,95

Abstract

Background: We examined the effect of major basic protein (MBP) stimulation on the expression of the neutrophilβ 2-integrins: LFA-1 (CD11a/CD18), CR3 (CD11b/CD18), and p150,95 (CD11c/CD18). Methods: Incubation of neutrophils with 0.75 to 3.0 μmol/L MBP for 30 minutes at 37 °C resulted in concentration-dependent increases in CR3 expression as detected by staining with the CD11b-specific monoclonal antibody, Leu-15. Results: The expression of CR3 was significantly (p < 0.001) higher when neutrophils were stimulated with 1.5 μmol/L (53% ± 9% increase) or 3.0 μmol/L (100% ± 17% increase) MBP as compared with unstimulated neutrophils. The kinetics of MBP-stimulated CR3 expression were rapid and were similar to those of 100 nmol/L N-formyl-methionyl-leucyl-phenylalanine-stimulated enhancement of CR3 expression. Incubation of neutrophils with reduced and alkylated MBP resulted in significantly lower (p < 0.05) increases in CR3 expression as compared with stimulation with native MBP. In addition, neither eosinophil cationic protein nor eosinophil-derived neurotoxin altered neutrophil CR3 expression. MBP stimulated minimal increases in LFA-1 expression. However, staining with the monoclonal antibody Leu-M5 (anti-CD11c) revealed that MBP stimulated significant increases in the expression of p150,95. Conclusions: These results indicate that MBP stimulates the increased expression of neutrophil adhesion molecules, which in turn may enhance the inflammatory role of neutrophils in the late-phase events of allergic diseases.