Immune inhibition of repair of canine skull trephine defects implanted with partially purified bovine morphogenetic protein.

The healing of 14-mm trephine skull defects was observed in ten adult mongrel dogs. First and second set trephine operations were performed to determine whether xenogeneic bovine bone morphogenetic protein (bBMP) and associated bone matrix water-insoluble noncollagenous proteins (iNCP) incite an immunological humoral response inhibiting bone repair. The effects of immunization to BMP/iNCP were observed by serum radioimmunoassay, and by correlated roentgenographic and histological analysis of deposits of new bone. The first set implants of bBMP/iNCP induced 96% healing while the regeneration of the second set trephines was 34% less than the first set. The second set was associated with a significant increase in serum anti-BMP antibodies. While xenogeneic bBMP induced complete healing of trephine defects when implanted without previous immunization, and repair in response to a second set of bBMP/iNCP was always incomplete, further research with high purified recombinant BMP is required to measure immune effects in a statistically significant number of pure bred recipients.