Surface phenotype of rat bone marrow-derived mononuclear phagocytes

Utilizing a panel of currently available monoclonal antibodies, the surface phenotype of a pure population of resting rat bone marrow-derived mononuclear phagocytes (BMMφ) was analyzed by means of flow cytometry. The present work provides an extensive list of surface markers expressed by BMMφ and also outlines advantages and limitations of flow cytometric analysis of this cell type. The results show that the majority of surface markers considered to be expressed selectively by T lymphocytes, such as Thy-1, CD2 and CD5 antigens, leukosialin (W3/13), or an alloantigen of peripheral T cells, are not expressed by BMMφ. On the other hand, the CD8 antigen and the leukocyte common antigen recognized by MRC OX-33, considered to represent specific markers of cytotoxic T cells and/or peripheral B cells, are expressed on a variable, often considerable proportion of BMMφ. Monoclonal antibodies W3/25, MRC OX-35, and MRC OX-38, directed against epitopes on the CD4 molecule, labeled a variable proportion of BMMφ. Among the 39 monoclonal antibodies examined, none appeared to recognize an epitope which is expressed selectively by mononuclear phagocytes.