Formation of osteoclast-like cells from peripheral blood of periodontitis patients occurs without supplementation of macrophage colony-stimulating factor

Aim: To determine whether peripheral blood mononuclear cells (PBMCs) from
chronic periodontitis patients differ from PBMCs from matched control patients in
their capacity to form osteoclast-like cells.
Material and Methods: PBMCs from 10 subjects with severe chronic periodontitis
and their matched controls were cultured on plastic or on bone slices without or with
macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear
factor-kB ligand (RANKL). The number of tartrate-resistant acid phosphatase-positive
(TRACP1) multinucleated cells (MNCs) and bone resorption were assessed.
Results: TRACP1 MNCs were formed under all culture conditions, in patient and
control cultures. In periodontitis patients, the formation of TRACP1 MNC was similar
for all three culture conditions; thus supplementation of the cytokines was not needed
to induce MNC formation. In control cultures, however, M-CSF or M-CSF/RANKL
resulted in higher numbers compared with cultures without cytokines. Upregulations
of osteoclast marker mRNA cathepsin K and carbonic anhydrase II confirmed the
osteoclastic character. Bone resorption was only observed when PBMCs were cultured
in the presence of M-CSF and RANKL.
Conclusion: Our data indicate that PBMCs from periodontitis patients do not need
priming by M-CSF to become osteoclast-like cells, suggesting that PBMCs from
periodontitis patients are present in the circulation in a different state of activity.