A monoclonal antibody with specificity for leukemic cells transformed by defective avian leukemia viruses

Abstract

Mouse anti‐chicken monoclonal antibodies were raised against an avian myeloblastosis virus (AMV)‐transformed myeloblastic leukemic cell line. One monoclonal antibody, S1‐37 (lgG2a), reacted with producer and nonproducer myeloblastic leukemia cell lines transformed by AMV and by E‐26 virus, but it did not react with chicken fibroblasts infected with RAV‐2, MAV‐2, MAV‐1, or RAV‐7, S1‐37 also did not react with normal chicken hemopoietic cells, except for yolk sack macrophages and a small population of embryonal and adult bone marrow cells that morphologically resembled macrophages. Cytotoxicity studies of GM‐CFU, the normal stem cell population of the granulocytic macrophage lineage, indicated that these cells lack the surface antigen recognized by S1‐37. Immunoprecipitation studies of ¹²⁵I surfacelabeled myeloblastic leukemic cells indicated that S1‐37 binds a 42,000 Mr polypeptide. The possible role of this polypeptide in the process of transformation and differentiation of chicken myeloid cells is discussed.