IMMUNOREACTIVITY AND PROLIFERATIVE ACTIONS OF BETA-2 MICROGLOBULIN ON HUMAN BONE-DERIVED CELLS-INVITRO

Recent studies have demonstrated homology between bone-derived growth factor and β2 microglobulin. We have shown that β2 microglobulin has proliferative actions on human bone-derived cells in vitro and that these cells also show immunogenicity for β2 microglobulin. β2 microglobulin stimulated the incorporation of 3H-thymidine into DNA of human bone cells in a dose-dependent manner. In contrast to this stimulatory action, β2 microglobulin had no detectable activity with the same concentration on the production of osteocalcin, alkaline phosphatase activity or prostaglandin E2 synthesis. The possibility that the human bone-derived cells could also produce β2 microglobulin was examined. Under basal conditions these cells exhibit immunoreactivity for β2 microglobulin, the expression of which could be enhanced following treatment with interferon γ in a dose-dependent manner. The co-localization of staining for β2 microglobulin and alkaline phosphatase, a marker of the osteoblast phenotype, indicate that human osteoblast-like cells represent a source of activity of this factor. The production of β2 microglobulin by human osteoblast-like cells and the subsequent action of this factor on cells within the bone microenvironment may indicate a role for β2 microglobulin as a local regulator of bone metabolism. © 1991.