Culture of macrophages from bovine bone marrow

Macrophages perform important immunoregulatory and host defense functions. Examination of this cell type in the bovine has been restricted because of lack of a means to obtain pure bovine macrophage populations reproducibly. We have developed a system for production of large numbers of macrophages from this species with greater than 99% purity. Stem cells were obtained from the bone marrow of neonatal calves and cultured in vitro in the presence of macrophage-colony-stimulating factor. Bovine bone marrow culture-derived macrophages were esterase-positive, expressed Fc receptors for aggregated IgG, and bovine macrophage differentiation markers. In addition, they displayed class I and class II major histocompatibility (MHC) antigens. The level of MHC antigen expressed could be further enhanced by treatment with recombinant bovine interferons. The macrophages exhibited expected functions, for example, Fc-mediated ingestion of opsonized sheep red blood cells. Augmentation of phagocytic capacity by either alpha or gamma interferon could also be demonstrated. The data reported here confirm that bone marrow culture is a convenient, reliable source of macrophages for investigations of this bovine cell type.