Eosinophil flow and static adhesion to MAdCAM-1.
(A) Flow chamber study. Eosinophils were infused at a flow rate of 0.7 dyn/cm2 into a parallel plate flow chamber containing MAdCAM-1–, VCAM-1–, or BSA-coated coverslips. The number of rolling eosinophils and adherent eosinophils during continuous flow periods of 2 minutes was recorded and subjected to offline analysis. Results of experiments performed are presented as the mean ± SEM (n = 4 experiments). At flow rates of 0.7 dyn/cm2, significant numbers of eosinophils rolled on VCAM-1 (P = .001 vs BSA) and adhered to VCAM-1 (P = .001 vs BSA). At the same flow rate, significantly fewer eosinophils rolled on MAdCAM-1 compared with VCAM-1 (P = .001) with few rolling eosinophils remaining firmly adherent to MAdCAM-1. (B) Static adhesion assay. Eosinophils were allowed to adhere for 30 minutes to a MAdCAM-1– or BSA-coated coverslip that had been subjected either to no shear stress (preflow panel) or to 1.4 dyn/cm2 shear stress (to simulate whether flow would strip MAdCAM-1 from the coverslip) (postflow panel). Nonadherent cells were then washed from the coverslip, and the coverslip was placed in the flow chamber. The number of adherent eosinophils was recorded on videotape. In the detachment panel, the eosinophils that had adhered to MAdCAM-1 (preflow panel) were subjected to shear stress (20 dyn/cm2) to determine whether the firmly adherent eosinophils were resistant to detachment from MAdCAM-1. There was no significant difference in the number of eosinophils adherent to MAdCAM-1 before and after application of shear force to the coverslip (preflow vs postflow) or after application of shear force to eosinophils adherent to MAdCAM-1 (P = not significant) (n = 3).
