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. Author manuscript; available in PMC: 2011 Aug 1.
Published in final edited form as: J Immunol. 2010 Jun 25;185(3):1878–1886. doi: 10.4049/jimmunol.1001305

Figure 7. Activating PECAM prior to adhesion inhibits transmigration.

Figure 7

(A) Monocytes were stimulated by PECAM cross-linking using the monoclonal anti-PECAM antibody P1.1 for the indicated times. Triton X100 soluble and insoluble fractions were analysed by western blotting. (B,C) Human monocyte transmigration through unstimulated HUVEC monolayers grown on collagen gels. Monocytes were prelabelled on ice with (B) non-blocking antibody against PECAM (P1.1), or (C) blocking antibody against PECAM (Hec7) at 20μg/ml, before being washed free of unbound antibody and added to HUVEC monolayers for 60 minutes. Cross-linking secondary antibodies (50μg/ml) were added at the start of the assay (t=0) or after 30 minutes (t=30) where indicated. Data represent mean ± SEM from 3 separate experiments, ** P<0.02, *** P<0.002. (D) Proposed model of leukocyte PECAM regulation during transendothelial migration. Leukocytes migrate to endothelial cell junctions where they homophilically engage PECAM. The subsequent phosphorylation of leukocyte PECAM drives as yet unknown mechanisms required for the continuation and completion of the transmigration process. After PECAM engagement, its phosphorylation and signaling in the leukocyte membrane is terminated by translocation to DRMs.