We describe a novel localization of C7 as
a membrane-bound molecule on endothelial
cells (ECs). Data obtained by sodium
dodecyl sulfate–polyacrylamide gel electrophoresis
(SDS-PAGE), Western blot
analysis, Northern blot analysis, and mass
spectrometry revealed that membraneassociated
C7 (mC7) was indistinguishable
from soluble C7 and was associated
with vimentin on the cell surface. mC7
interacted with the other late complement
components to form membrane-bound
TCC (mTCC). Unlike the soluble SC5b-9,
mTCC failed to stimulate ECs to express
adhesion molecules, to secrete IL-8, and
to induce albumin leakage through a
monolayer of ECs, and more importantly
protected ECs from the proinflammatory
effect of SC5b-9. Our data disclose the
possibility of a novel role of mC7 that acts
as a trap for the late complement components
to control excessive inflammation
induced by SC5b-9.
