Unique high and homogenous surface expression of the transferrin receptor CD71 on murine plasmacytoid dendritic cells in different tissues.

Plasmacytoid dendritic cells (pDC) are of increasing interest in cancer vaccine development, but many functions of these highly specialized, multifaceted cells are poorly understood. The transferrin receptor CD71 has also been suggested to function as an antigen uptake receptor on professional antigen-presenting cells. In this study, we employed multiparameter flow cytometry to investigate CD71 expression on various leukocyte subsets, including DC subsets, granulocytes, macrophages, T and B lymphocytes, γδ T cells, and natural killer cells. Cells from various lymphoid and non-lymphoid murine tissues were analyzed using fluorochrome-conjugated monoclonal antibodies. High CD71 expression (90-100%) was observed, uniquely on pDC amongst the leukocyte populations examined, in both lymphoid and non-lymphoid tissues, including other DC subsets. In contrast, CD71 expression on non-tissue pDC, in the bone marrow and peripheral blood, was reduced. The cause and function of this high tissue pDC-selective CD71 expression remain to be examined.