The Effects of Osteoclast-Activating Factor (OAF) on the Absorption of Alveolar Bone: 1. Production and Purification of OAF

We have characterized osteoclast-activating factor (OAF) using a bioassay for bone resorption which utilizes the release of 45Ca from fetal rat calvaria in vitro. OAF was obtained from supernatants of cultures of either normal human leukocytes (PBL), or tonsil cells activated with phytohemagglutinin (PHA) or dental plaques from patients with periodontal disease. Furthermore, T and non-T cells were separated from PBL by means of sheep erythrocyte rosette formation, and each fraction was cultured with PHA. The results suggest that activated T cells can produce OAF, and its production is enhanced by plastic-adherent cells (monocyte). 100% of the OAF activity was retained on Amicon UM2 membranes with a nominal molecular weight cutoff of 1, 000 daltons, and 60% of the activity was retained on Amicon PM 10 membranes with a nominal molecular weight cutoff of 10, 000 daltons. These results indicate that the molecular weight of OAF is about 10, 000 daltons.