CONTINUOUS CULTURES OF MACROPHAGES DERIVED FROM THE 8-DAY EPIBLAST OFTHE PIG

Secondary macrophage cell cultures were generated from the primary cul ture of epiblasts of 8-d-old pig blastocysts. The epiblast-derived mac rophagelike (EDM) cells have a morphology and ameboid behavior that is typical of tissue histocytes. The cells reacted positively with monoc lonal antibodies specific for pig granulocyte-macrophage lineage cells , and were not reactive with monoclonal antibodies specific for pig B and T lymphocytes. Marked phagocytic behavior and the formation of pha gosomes were demonstrated following incubation with FITC-labeled bacte ria. The EDM cells stained positively for nonspecific acid esterase th at was not inhibited by sodium fluoride. Dil-acetylated-LDL was rapidl y taken up by the cells. Transmission electron microscopy of the EDM c ells showed phagolysosomes, numerous cytoplasmic vacuoles, large, lobe d nuclei, and numerous pseudopods or filopodia at the cell surface. St rong reactivity of the cells with anti-CD14 monoclonal antibody was ob served. Further, cytotoxic activity was produced from the EDM cells af ter exposure to lipopolysaccharide in a concentration and time-depende nt manner. The cultures could be maintained and expanded for several m onths on STO co-culture. Their derivation from the epiblast of the pig demonstrates the possibility of obtaining hemopoietic cell cultures f rom the preimplantation blastocysts of all mammals.