Decay-accelerating factor is expressed on vascular smooth muscle cells in human atherosclerotic lesions.
Decay-accelerating factor (DAF) is a constitutively expressed plasma membrane glycoprotein on blood cells and endothelium that inhibits cell surface C3/C5 convertase formation, thus inhibiting complement activation and protecting cells from lysis by the terminal complement components. Using monoclonal anti-DAF antibodies in conjunction with anti-smooth muscle cell (SMC)-specific myosin antibodies, it was found by immunohistochemistry that vascular SMC in advanced human carotid atherosclerotic lesions express DAF antigen. The percentage of DAF-positive SMC ranged from 20 to 60% between different patient samples and SMC DAF expression was limited to SMC in the lesion proper. Normal arterial wall SMC exhibited no DAF-specific immunostaining. Essentially 100% of passaged cultured vascular SMC derived from normal human uterine artery, or from umbilical vein, expressed DAF as assessed by immunocytochemistry. A 68-kD band was observed on SDS-PAGE autoradiograms of DAF-immunoprecipitated radiolabeled cultured SMC extracts. Sensitization of rabbit erythrocytes with DAF-containing SMC extracts conferred protection against complement-mediated hemolysis in normal human serum and the protective effect could be reversed by treatment with anti-DAF antibodies. We conclude that DAF is induced on vascular SMC during atherogenesis and in culture.
Seifert
P S
PS
Department of Clinical Chemistry, Gothenburg University, Sahlgren's Hospital, Sweden.
Hansson
G K
GK
D001161:Arteriosclerosis / Q000378:metabolism*; D018958:CD55 Antigens; D002478:Cells, Cultured; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis* / Q000276:immunology / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000032:analysis*
D018958:CD55 Antigens; D006023:Glycoproteins; D008565:Membrane Proteins