STIMULATION OF OSTEOCLAST-LIKE CELL-FORMATION BY PASTEURELLA-MULTOCIDA TOXIN FROM HEMATOPOIETIC PROGENITOR CELLS IN MOUSE BONE-MARROW CULTURES

The effects of purified Pasteurella multocida toxin (PMT) on osteoclas t formation from hemopoietic progenitor cells were studied using an in vitro system, Mononuclear adherent mouse bone marrow cells were cultu red for 7 or 14 days in the presence of PMT, or 1,25-dihydroxy-vitamin D-3, or both, Mononuclear osteoclast-like cells, which are postmitoti c osteoclast precursor cells, were identified as tartrate-resistant ac id phosphatase (TRAP)-positive mononuclear cells possessing calcitonin receptors, Multinucleated osteoclast-like cells were TRAP-positive mu ltinuclear cells with calcitonin receptors, The results demonstrate th at, as does 1,25(OH)(2)D-3, Pasteurella multocida toxin stimulates pro liferation of adherent bone marrow mononuclear cells (progenitor cells ), and their differentiation into postmitotic mononuclear osteoclast p recursor cells. It also causes fusion of the latter into multinuclear osteoclasts; however, the number of osteoclasts obtained with PMT is s maller than with 1,25-dihydroxy-vitamin D-3.