EOSINOPHIL MAJOR BASIC-PROTEIN ENHANCES THE EXPRESSION OF NEUTROPHIL CR3 AND P150,95

Background: We examined the effect of major basic protein (MBP) stimul ation on the expression of the neutrophil beta2-integrins: LFA-1 (CD11 a/CD18), CR3 (CD11b/CD18), and p150,95 (CD11c/CD18). Methods: Incubati on of neutrophils with 0.75 to 3.0 mumol/L MBP for 30 minutes at 37-de grees-C resulted in concentration-dependent increases in CR3 expressio n 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 mumol/L (53% +/- 9% i ncrease) or 3.0 mumol/L (100% +/- 17% increase) MBP as compared with u nstimulated neutrophils. The kinetics of MBP-stimulated CR3 expression were rapid and were similar to those of 100 nmol/L. N-formyl-methiony l-leucyl-phenylalanine-stimulated enhancement of CR3 expression. Incub ation of neutrophils with reduced and alkylated MBP resulted in signif icantly 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 expre ssion. MBP stimulated minimal increases in LFA-1 expression. However, staining with the monoclonal antibody Leu-M5 (anti-CD11c) revealed tha t MBP stimulated significant increases in the expression of p150,95. C onclusions: These results indicate that MBP stimulates the increased e xpression of neutrophil adhesion molecules, which in turn may enhance the inflammatory role of neutrophils in the late-phase events of aller gic diseases.