Monoclonal antibody to human eosinophils recognizing 95 kD surface membrane antigen

Mice were immunized with purified eosinophils obtained from patients with the idiopathic hypereosinophilic syndrome. A hybridoma initially producing an IgM antibody which switched to an IgG1 antibody was selected for cloning and further testing. This IgG1 antibody reacted with human eosinophils, granulocytes, monocytes and large granular lymphocytes, but did not react with T lymphocytes, B lymphocytes, platelets, erythrocytes, or a panel of human leukemia cells and cell lines. Bone marrow analysis revealed staining of myeloid precursor cells but not erythroid precursors or plasma cells. This IgG1 antibody had no effect on aggregation of granulocytes, lysozyme release, superoxide production, chemotaxis, or killing activity; however, there was some stimulation of beta-glucuronidase secretion. While the antibody did not augment the killing of Staphylococcus aureus by granulocytes, the antibody itself was bactericidal. By immunoprecipitation of granulocytes, eosinophils and monocytes, a molecule with a molecular weight of 95 kD was identified.