H. Usuda et al., ULTRASTRUCTURE OF MACROPHAGES AND DENDRITIC CELLS IN OSTEOPETROSIS (OP) MUTANT MICE LACKING MACROPHAGE-COLONY-STIMULATING FACTOR (M-CSF CSF-1) ACTIVITY/, Journal of submicroscopic cytology and pathology, 26(1), 1994, pp. 111-119
The ultrastructural features of macrophages and dendritic cells of mic
e homozygous for osteopetrosis (op/op) mutation were studied. The muta
nt mice are characterized by defective differentiation of osteoclasts,
monocytes, and tissue macrophages due to the lack of functional macro
phage colony stimulating factor (M-CSF/CSF-1) activity. In op/op mice,
tissue macrophages were reduced in number and smaller than in normal
littermates. Macrophages in op/op mice showed various degrees of phago
cytosis but the development of intracytoplasmic organelles and microvi
llous projections was poor. After administration of CSF-1 daily for 2
weeks, macrophases in op/op mice developed lysosomes and microvillous
projections. In the thymic medulla, T-cell zone of I;mph nodes, spleni
c white pulp and epidermis of the op/op mice, the number of dendritic
cells was similar to that in normal littermates and the dendritic cell
s developed a tubulovesicular system typical of interdigitating cells.
Birbeck granules in epidermal Langerhans cells were detected in unman
ipulated op/op mice, op/op mice injected with CSF-1, and normal litter
mates or control mice. However, in untreated op/op mice, dendritic cel
ls projected shorter cytoplasmic processes than in normal littermates,
normal control mice and CSF-1 injected op/op mice. These results indi
cate that the differentiation and maturation of tissue macrophages are
mediated by CSF-1, but the dendritic cell differentiation is controll
ed by other factor(s) than CSF-1, most probably by GM-CSF.