[Effect of activated macrophages on cultured fibroblasts of the spinal posterior longitudinal ligament of the rabbit].

The present study was performed to elucidate the ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. The relationship between OPLL and active oxygen was investigated using cultured fibroblasts derived from the spinal posterior longitudinal ligament of rabbit. Alveolar macrophages obtained from the same rabbit inoculated with Bacillus Calmette-Guerin (BCG) was added in the tissue culture system. The macrophages display a greatly enhanced power to generate O2- when stimulated by polystyrene latex spherules, 10-fold higher than treated with NaF. The cultured fibroblasts were directly connected with activated alveolar macrophages, then morphological changes and outgrowths were studied by phase contrast microscope. A significant effect was observed after in vitro exposure to 6 x 10(6) activated macrophages; the cells became greatly differentiated within 30 min, then proliferated and grew into multilayer after 6 days of culture. It is difficult to prove that the activated macrophages are a primary cause of OPLL, but the evidence presented here suggests that the active oxygen and other products derived from macrophages may give osteogenic potentiality to the cells in the spinal posterior longitudinal ligament.