Thy-1 (CD90) is an interacting partner for CD97 on activated endothelial cells

E Wandel, A Saalbach, D Sittig… - The Journal of …, 2012 - journals.aai.org
E Wandel, A Saalbach, D Sittig, C Gebhardt, G Aust
The Journal of Immunology, 2012journals.aai.org
Leukocyte recruitment in response to inflammatory signals is governed, in part, by binding to
Thy-1 (CD90) on activated endothelial cells (EC). In this study, we characterized the
adhesion G-protein coupled receptor CD97, present on peripheral myeloid cells, as a novel
interacting partner for Thy-1. CD97 was upregulated on polymorphonuclear cells (PMNC) of
patients with psoriasis. In psoriatic skin lesions, CD97+ myeloid cells colocalized with Thy-
1+ EC of small vessels in microabscesses, suggesting an interaction between CD97 and …
Abstract
Leukocyte recruitment in response to inflammatory signals is governed, in part, by binding to Thy-1 (CD90) on activated endothelial cells (EC). In this study, we characterized the adhesion G-protein coupled receptor CD97, present on peripheral myeloid cells, as a novel interacting partner for Thy-1. CD97 was upregulated on polymorphonuclear cells (PMNC) of patients with psoriasis. In psoriatic skin lesions, CD97+ myeloid cells colocalized with Thy-1+ EC of small vessels in microabscesses, suggesting an interaction between CD97 and Thy-1 that was further examined by adhesion and protein-binding assays. PMNC and cell lines stably overexpressing CD97 adhered specifically to Thy-1+–activated human dermal EC, Thy-1+ CHO cells, and immobilized Thy-1 protein. Binding of the CD97+ CHO clones correlated with their CD97 expression level. Soluble CD97 bound specifically to immobilized Thy-1 protein, as well as Thy-1+–activated EC and CHO cells. In all assays, cellular adhesion or protein binding was blocked partially by CD97 and Thy-1–blocking mAb. Our data suggested that CD97 interacts via its stalk with Thy-1 because mAb directed to the stalk of CD97 showed stronger blocking compared with mAb to its epidermal growth factor-like domains, and binding was calcium independent. Moreover, soluble CD97 without the stalk and soluble EMR2, containing highly homologous epidermal growth factor-like domains but a different stalk, failed to bind. In summary, binding of leukocytes to activated endothelium mediated by the interaction of CD97 with Thy-1 is involved in firm adhesion of PMNC during inflammation and may play a role in the regulation of leukocyte trafficking to inflammatory sites.
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