Differentiation of dendritic cell populations in macrophage colony-stimulating factor-deficient mice homozygous for the osteopetrosis (op) mutation.

In op/op mice, immunohistochemical and electron microscopic techniques were used to examine the effects of the OP mutation on dendritic cell populations in lymphoid tissues and skin. In the thymic medulla, T cell zone of lymph nodes, and splenic white pulp of op/op mice, numbers of NLDC-145-positive dendritic cells were not decreased. Compared to the normal littermates, numbers of BM8-positive macrophages were reduced in various tissues of the mutant mice, including the lymphoid tissues. These dendritic cells of op/op mice expressed Ia antigens but not F4/80 and BM8 antigens. Ultrastructurally, the dendritic cells developed a tubulovesicular system typical of interdigitating cells, but they were abnormal in that interdigitation of their cytoplasmic processes was not prominent. In the epidermis of the op/op mice, dendritic cells expressed NLDC-145, F4/80, Ia antigens, and adenosine diphosphatase or adenosine triphosphatase activity, and numbers of NLDC-145-, Ia-, or ADPase-positive dendritic cells were reduced slightly, but these reductions were not significant statistically. Birbeck granules were detected in most of them electron microscopically. These results indicate that nonlymphoid dendritic cells develop in the lymphoid tissues and skin of op/op mouse, suggesting that they are differentiated from granulocyte-macrophage colony-forming cells or earlier hematopoietic cell precursors.