Morphologic effects of antibody to mouse brain endothelium in vivo.

The purpose of this study was to assess the morphologic effects of antiendothelial antibodies (EAB) on mouse brain endothelium in vivo. The antigen utilized was the plasma membranes fraction of cultured mouse brain endothelial cells, which was injected into rabbits with complete Freund's adjuvant. The resultant antibody-containing serum was injected back into mice via tail veins in varying time courses and dosages, followed by perfusion of the animals. The antibody was primarily IgG, and was visualized on the brain endothelium by electron microscopy, using the peroxidase antiperoxidase (PAP) labeling technique. Normal rabbit sera and saline were used as controls. Results showed a significantly greater number of micropinocytotic vesicles in the endothelium of the test animals compared to controls. The number of multivesicular bodies and the thickness of the endothelium were also greater in the test animals. At no time was antibody visualized internal to the endothelial luminal membrane, and no lesions such as inflammation or necrosis were observed. This study shows that serum-containing antiendothelial antibodies has a direct, but apparently limited, effect on endothelium.