CHARACTERIZATION OF MURINE MONOCLONAL ANTIENDOTHELIAL CELL ANTIBODIES(AECA) PRODUCED BY IDIOTYPIC MANIPULATION WITH HUMAN AECA

The IgG fraction of human anti-endothelial cell antibodies (AECA) obta ined from a patient with Wegener's granulomatosis was used as immunoge n to raise AECA mAb in mice selected among those which developed vascu litis-like lesions after immunization. Three mAb (BGM, 3C8 and 7G2), s elected by cyto-ELISA and flow cytometry analyses, featured a specific reactivity with human umbilical vein endothelial cells (HUVEC) and th e mouse endothelial cell line H5V; on the contrary, HEp2 cells, the mu rine melanoma B16 cell line, the extracellular matrix as well as sever al other antigens tested were not recognized. BGM mAb, an IgG3 precipi tating a 70 kDa structure from HUVEC, was able to induce endothelial c ells to secrete amounts of IL-6 significantly higher than irrelevant c ontrols or mAb binding different endothelial antigens (i,e. CD31, CD29 , ICAM-1 and HLA class I). BGM mAb induced significant levels of antib ody-dependent cell cytotoxicity(13 +/- 2.5 versus 0.6 +/- 0.03%), To t he best of our knowledge, BGM is the first murine mAb specific for hum an endothelial cells generated by idiotypic manipulation; secondly, it s biological properties further support the notion of a pathogenic rol e for AECA in autoimmune-mediated diseases.