MYELOID-ASSOCIATED DIFFERENTIATION ANTIGENS ON STEM-CELLS AND THEIR PROGENY IDENTIFIED BY MONOCLONAL-ANTIBODIES

Abstract

Within the hematopoietic system, monoclonal antibodies reactive with antigenic determinants, expressed in a lineage- and stage-restricted fashion, can be used to map myeloid differentiation. A series of monoclonal antibodies that reacts with myeloid-associated determinants on commmitted myeloid stem cells and their progeny was developed. Their reactivity with [human] peripheral blood cells was identified by immunofluorescence assays, with bone marrow cells by fluorescence-activated cell sorting, and with committed hematopoietic progenitor cells by both cytotoxic assays and fluorescence-activated cell sorting. Antibody 1G10, which has previously been reported to react with cells of the granulocytic lineage and with a minor subset of mature monocytes, was shown to react with granulocyte-macrophage colony-forming units (CFU-GM). Three antibodies not previously characterized (T5A7, L4F3, L1B2) reacted with both granulocytic and monocytic cells and in fluorescence-activated cell sorting studies to detectably stain granulocytic cells at diffferent stages of maturation. These 3 antibodies also react with CFU-GM, two (L4F3 and L1B2) reacting with all CFU-GM, while T5A7 reacts with only a portion of the day 7 CFU-GM. Antibody L4F3 also reacts with a portion of erythroid burst-forming units. The previously reported antibody 5F1, which reacts with monocytic cells, nucleated erythroid cells and platelets, reacted with erythroid colony-forming units. Potential applications of these antibodies to studies of normal and malignant hematopoiesis are discussed.