Characterization of ICAM-2 and evidence for a third counter-receptor for LFA-1.

Abstract

In an endeavor to further characterize human intercellular adhesion molecule-2 (ICAM-2), two murine monoclonal antibodies (mAb) were generated to ICAM-2 transfected COS cells, and designated CBR-IC2/1 and CBR-IC2/2. Immunoprecipitated, reduced ICAM-2 migrated as a broad band of Mr 60,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Treatment with N-glycanase revealed a peptide backbone of Mr 31,000, consistent with the size predicted from the cDNA. ICAM-2 had a broad distribution on hematopoietic cell lines and little expression on other cell lines, the sole exception being cultured endothelial cells which possess high levels of ICAM-2. Resting lymphocytes and monocytes expressed ICAM-2, while neutrophils did not. Staining of tissue sections with anti-ICAM-2 mAb confirmed their strong reactivity to vascular endothelium, but demonstrated a lack of ICAM-2 expression on other tissues. Small clusters of ICAM-2 positive cells were, however, seen in germinal centers. In contrast to ICAM-1 there was little or no induction of ICAM-2 expression on lymphocytes or cultured endothelium upon stimulation with inflammatory mediators. One of the two mAb, CBR-IC2/2, was found to totally inhibit binding of ICAM-2+ COS cells to purified lymphocyte function-associated antigen-1 (LFA-1). Using this mAb, LFA-1-dependent binding to both stimulated and unstimulated endothelium was found to be totally accounted for by ICAM-1 and ICAM-2. Homotypic aggregation of an Epstein-Barr virus-transformed B cell line, JY, was found to be solely ICAM-1 and ICAM-2-dependent, while in the case of the T cell lymphoma cell line, SKW3, anti- ICAM-2 mAb in conjunction with anti-ICAM-1 mAb could not inhibit the LFA-1-dependent aggregation. This suggests an additional LFA-1 ligand exists. Using a cell binding assay to purified LFA-1 in conjunction with anti-ICAM-1 and anti-ICAM-2 mAb, we have demonstrated that this putative third ligand for LFA-1 exists on SKW3 and other cell lines.

The isolation and culture of endothelial colony-forming cells from human and rat lungs

“…Rat ECFCs express endothelial surface markers VCAM-1 and ICAM-2 15,24 . They also express CD34 and c-Kit, cell-surface antigens previously identified on endothelial and hematopoietic progenitor cells 15,25 (Figure 7).…”

Migration of immature mouse DC across resting endothelium is mediated by ICAM‐2 but independent of β2‐integrins and murine DC‐SIGN homologues

“…These proteins were shown to serve as ICAM-2 ligands on other leukocytes [13,15,16]. We therefore expected these molecules to account for the ICAM-2-dependent TEM of immature DC.…”

“…Geijtenbeek et al [12] have shown that this interaction enables rolling of DC-SIGN-transfected cells on ICAM-2 and transmigration of DC across endothelial monolayers. For homeostatic extravasation of DC, the DC-SIGN-ICAM-2 interaction is of particular interest since ICAM-2 is constitutively expressed on endothelium and does not require inflammatory stimuli for high-density expression as do other endothelial adhesion molecules like ICAM-1 and the endothelial selectins [13,14]. In this respect it is especially interesting that Geijtenbeek et al [12] found that the DC-SIGN-ICAM-2 interaction does mediate migration of immature DC not only across activated but also across resting endothelium.…”

“…In this respect it is especially interesting that Geijtenbeek et al [12] found that the DC-SIGN-ICAM-2 interaction does mediate migration of immature DC not only across activated but also across resting endothelium. In fact, transmigration across non-activated endothelial monolayers was largely dependent on this interaction with only a minimal contribution of b 2 -integrins (CD11/CD18), which are the principal interaction partners of ICAM-2 on many other types of leukocytes [13,15,16]. Thus, in humans, DC interactions with ICAM-2 on resting endothelium appear to be mediated by DC-SIGN rather than b 2 -integrins.…”

Unique Structural Features That Influence Neutrophil Emigration Into the Lung

“…ICAM-2 (CD102) is constitutively expressed on vascular endothelial cells (45) and is a ligand for leukocyte ␤ 2 -integrins CD11a/CD18 and CD11b/CD18 (145,249,291). In vitro, ICAM-2 appears to play a role in neutrophil (116) and eosinophil (83) transendothelial migration.…”