Demonstration of a C1q receptor on the surface of human endothelial cells.

A receptor for C1q on the surface of human endothelial cells has been demonstrated. This receptor is present on the surface of viable cultured endothelial cells derived from human umbilical veins, and C1q binding can also be demonstrated to the endothelial lining cells of human umbilical artery and vein on frozen tissue sections. Receptors for the complement components C3b and C3d were not detected on tissue sections or endothelial cells in suspension. Endothelial cell C1q receptors are discussed in relationship to possible immune complex localization in vivo.