PHENOTYPIC CHARACTERIZATION OF MONONUCLEAR-CELLS FOLLOWING ANORGANIC BOVINE BONE IMPLANTATION IN RATS

THE PURPOSE OF THIS STUDY was to measure inflammatory changes associat ed with implantation of anorganic bovine bone and bovine bone/collagen composite grafts, and to compare the response to that obtained follow ing grafting with hydroxyapatite. Anorganic bovine bone, either with o r without bovine collagen, as well as granular and block forms of synt hetic hydroxyapatite, were implanted subcutaneously in Wistar rats. Sa line and turpentine oil were used as controls. Biopsies were obtained after 3 days and at 1, 2, 4, 6, and 8 weeks. A panel of 6 monoclonal a ntibodies was used to detect monocytes, several distinct macrophage su bsets, Ia-antigen expression, and T- and B-lymphocytes. Cells identifi ed by each antibody were counted after immunocytochemical staining, an d sera obtained 6 weeks after grafting were used in immunoblotting ass ays to detect antibodies to bovine serum proteins and collagen. Anorga nic bovine bone, bovine bone/collagen, and hydroxyapatite all produced a transient macrophage infiltrate that was maximum 3 days after impla ntation, but resolved to normal levels within 6 to 8 weeks. Lymphocyte infiltration was not elicited by any bovine graft material, and antib odies to bovine serum proteins or type I collagen were not detected in any of the animals examined. These data indicate that a systemic or l ocal immune response does not develop following implantation with anor ganic bovine bone or with anorganic bovine bone/collagen materials. It appears appropriate to explore further the merits of these materials for periodontal regenerative procedures.