Phenotypic analysis of ovine bone marrow cells using monoclonal antibodies and lectins

Three major subpopulations of ovine bone marrow cells were identified by flow cytometry on the basis of differences in forward (FSC) versus right angle (SSC) light scattering properties and binding of monoclonal antibodies. Region 1 (low FSC, low SSC) contained erythroid series cells and some small lymphocytes. Region 2 (high FSC, low SSC) contained monocytes, myeloid blast cells, medium-large lymphocytes and virtually all of the progenitor/stem cells capable of forming colonies in soft agar cultures. Region 3 (high SSC) contained granulocytes at various stages of development, predominantly (greater than 90%) neutrophils and eosinophils. Using this technique it was possible to identify several cell-surface antigens on bone marrow cells of different lineages using specific monoclonal antibodies and lectins. Amongst the haemopoietic stem/progenitor cell population, immature colony-forming cells were leucocyte common antigen (LCA) negative while more mature colony-forming cells expressed LCA. A proportion of progenitor cells were MHC class I positive. This analysis is an important first step in characterising ovine haemopoietic cells for future studies on: the development of inflammatory cells, the migration of stem/progenitor cells in vivo and the tropism of pathogens.