A MONOCLONAL-ANTIBODY TO AN OVINE GP130 MOLECULE INHIBITS HOMOTYPIC AGGREGATION INDUCED BY ANTI-CD43 MONOCLONAL-ANTIBODIES OF RUMINANT LEUKOCYTES

A monoclonal antibody (mAb) Co.3E1D4 which recognized a molecule prese nt on the surface of ovine peripheral blood granulocytes, monocytes, p latelets and a small percentage of lymphocytes, was able to block leuk ocyte aggregation induced by mAbs specific for the leukosialin or CD43 molecule. Co.3E1D4 precipitated an antigen with apparent molecular we ight of 130 kDa (under reducing and non-reducing conditions). Endoglyc osidase F digestion of the molecule resulted in reduction in the appar ent molecular weight. These data suggest that the antigen recognized b y Co.3E1D4 may be homologous to the human CD31 or platelet endothelial cell adhesion molecule-1 (PECAM-1). Aggregation produced by other ind ucers such as PMA was not blocked showing that only some cell-cell int eractions were mediated by the gp130 molecule.