It has previously been shown that monoclonal antibody M1-8 can recognize murine dendritic cells (DC) in the skin and T-dependent area of lymphoid organs. Recently we found some peripheral blood mononuclear cells (PBMC) and bone marrow cells (BMC) that also express M1-8 antigen. In order to get closer to the origin of DC, we characterized these cells in this study. Flow cytometry showed that 1%-4% of PBMC and 15%-30% of BMC were positive for M1-8 antigen. Most of M1-8-positive BMC also expressed ER-MP 20 antigen, a marker of macrophage precursors, although no mature monocytes in the peripheral blood reacted with the M1-8 antibody. Among the M1- 8-positive cells, a higher percentage of PBMC than BMC expressed Thy 1.2 and 1a antigen, while M1-8-reactive BMC more frequently expressed Fc receptors than PBMC. Therefore, more M1-8-positive BMC showed monocytoid characters than PBMC. Ultrastructurally, M1-8 antibody reacted to the cytoplasm of the lymphocyte-like cells both in the bone marrow and peripheral blood. In addition, some cells with monoblastoid/cytoid morphology and immature peroxidase-positive granules were also M1-8-positive in the bone marrow. Our results suggest that M1-8-positive PBMC and BMC could be immature cells of monoblastoid/cytoid origin, distinct from classic monocytes, and they may serve as precursors for peripheral DC.
|Number of pages||6|
|Journal||Cell Vision - Journal of Analytical Morphology|
|Publication status||Published - jan. 1 1996|
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