Activated T cells acquire endothelial cell (EC) plasma membrane constituent
s during transendothelial migration. This was assessed using an in vitro mo
del system in which human peripheral blood CD4(+) T cells migrated through
conflueut monolayers of HUVEC, Flow cytometry of migrated CD4(+) T cells de
monstrated that activated, but not resting, T cells acquired a variety of e
ndothelial surface determinants, including CD31, CD49d, CD54, CD61, and CD6
2E, The extracellular domains of these molecules were detected on migrated
T cells with mAbs, including those directed to the ligand-binding regions.
A number of approaches were employed to document that the acquisition of th
ese molecules was uniquely accomplished by activated T cells and clearly in
volved transfer from both resting and TNF-alpha-activated EC, Acquisition o
f endothelial markers by activated T cells occurred as part of the transfer
of membrane components, as migrating T cells acquired EC membranes prelabe
led with the lipophilic dye, 3'-dihexadecyloxacarbocyanine perchlorate (DiO
C-16), along with EC surface proteins. Thus, during transendothelial migrat
ion, activated T cells acquire endothelial membrane components, and as a re
sult may deliver them to perivascular sites.