A MONOCLONAL-ANTIBODY DETECTS HETEROGENEITY IN VASCULAR ENDOTHELIUM OF TUMORS AND NORMAL-TISSUES

A new murine monoclonal antibody (MAb), E-9, has been raised using tis sue-cultured human umbilical vein endothelial cells. The antigen recog nized by this MAb is a peptide of 170 kDa under non-reducing condition s and 96 kDa under reducing conditions. MAb E-9 showed marked heteroge neity in its distribution in various tissues. The antigen recognized b y it was present in vascular endothelial cells of all tumours, foetal organs and in regenerating and inflamed tissues. It stained a few norm al tissues. However, with the exception of tonsils, staining tended to be weak and limited to a few blood vessels, as revealed by double sta ining using pan-endothelial antibody (CD3 1) and antibody to von Wille brand factor, another marker of vascular endothelium. Surprisingly, bl ood vessels within the placental villi were completely negative. The f unction of the antigen recognized by MAb E-9 is not known, but its eva luation and use should increase our understanding of angiogenesis.