A human granulocyte-specific antigen characterized by use of monoclonal antibodies

Hybridoma cell lines secreting monoclonal antibodies that bind to a surface antigen of human neutrophils have been prepared by fusion of mouse myeloma cells with spleen cells from mice immunized with human neutrophils. Several of the monoclonal antibodies (AHN 1–6) were specific for a neutrophil surface antigen and did not bind lymphocytes, monocytes, red blood cells, platelets, or basophils. All of the granulocyte-specific antibodies immunoprecipitated a polypeptide of 145,000 daltons and an isoelectric point of about 4.5 and other heterogeneous polypeptides of 105,000 daltons. These same components were the major lactoperoxidase-labeled proteins precipitated by hyperimmune mouse serum. The antibodies were further characterized for binding to several human myeloid leukemia cell lines and cells from patients with myeloid or lymphoid leukemia. All antibodies bound the HL- 60, ML1, ML2, ML3, K562, and U937 myeloid leukemia cell lines. None of the antibodies bound the RPMI 6410 Raji, RPMI 8226, MOLT 4, or Daudi lymphoid cell lines. All of the hybridoma cell lines (AHN 1–6) produced IgM antibodies that were cytotoxic.