Related Experiment Videos
Binding of human peripheral blood polymorphonuclear leukocytes to E-selectin (CD62E) does not promote their
H Repo1, Y P Rochon, B R Schwartz
1Department of Medicine, University of Washington, Seattle 98195, USA. herepo@cc.helsinki.fi
Abstract:
E-selectin (CD62E) is a cytokine-inducible endothelial cell adhesion molecule that tethers polymorphonuclear leukocytes (PMNs) and supports PMN rolling under conditions of flow. We examined whether interaction of PMNs with E-selectin also leads to activation of CD11b/CD18 (Mac-1, alphaMbeta2), an event that can promote firm adhesion. PMNs were added to monolayers of IL-1beta-activated HUVECs and Chinese hamster ovary (CHO) cells transfected with E-selectin cDNA. PMN activation was assessed by 1) increased CD11b/CD18 surface expression, 2) appearance of activation epitope on CD11b/CD18 (CD11b*) detected by mAb CBRM1/5, and 3) decreased L-selectin (CD62L) expression, as determined by flow cytometry. Both adherent and nonadherent supernatant PMNs became activated on IL-1beta-pretreated HUVECs. This activation was not affected by CD62E-blocking mAb P6E2. The activation state of PMNs adhered to CHO cells transfected with E-selectin cDNA was not increased over background and was similar to that of PMNs exposed to parent CHO cells. The findings were confirmed using confocal microscopy, which allowed staining of the cells for CD11b* in situ. In concert, the results suggest that PMN binding to E-selectin does not elicit inter-receptor signaling that could result in strengthening of PMN adhesion to endothelium.
Insights
Polymorphonuclear leukocytes (PMNs) binding to E-selectin does not activate CD11b/CD18. This suggests E-selectin interaction alone does not promote firm adhesion, impacting our understanding of inflammatory responses.
Area of Science:
- Immunology
- Cell Biology
- Biochemistry
Background:
- E-selectin (CD62E) is an adhesion molecule on endothelial cells that binds polymorphonuclear leukocytes (PMNs), facilitating their rolling under flow.
- Activation of PMNs, indicated by CD11b/CD18 (Mac-1) upregulation, is crucial for firm adhesion during inflammation.
- It remains unclear whether E-selectin engagement alone triggers PMN activation.
Purpose of the Study:
- To investigate if the interaction between PMNs and E-selectin leads to the activation of CD11b/CD18.
- To determine if E-selectin binding alone can induce signaling pathways that enhance PMN adhesion.
Main Methods:
- PMNs were incubated with IL-1beta-activated human umbilical vein endothelial cells (HUVECs) and E-selectin-transfected Chinese hamster ovary (CHO) cells.
- PMN activation was assessed using flow cytometry to measure surface expression of CD11b/CD18, the activation epitope CD11b*, and L-selectin (CD62L) levels.
- Confocal microscopy was employed to visualize CD11b* expression in situ.
Main Results:
- PMNs interacting with IL-1beta-activated HUVECs showed activation, but this was independent of E-selectin.
- PMNs adhering to E-selectin-transfected CHO cells did not exhibit increased CD11b/CD18 activation compared to controls.
- Blocking E-selectin with a specific antibody did not alter PMN activation on HUVECs.
Conclusions:
- PMN binding to E-selectin does not induce CD11b/CD18 activation.
- E-selectin engagement alone does not appear to trigger the necessary inter-receptor signaling for firm PMN adhesion.
- These findings suggest that other adhesion molecules or signaling pathways are required for robust PMN recruitment in inflammation.