Immunological response of allogeneic bone grafting: a systematic review of prospective studies

BACKGROUND: Although widely used, the potential for immunological sensitization of allogeneic bone grafts is still controversial in the literature. This systematic review aimed to evaluate the immune response of allogeneic bone graft procedures in humans. METHODS: An electronic search without language or date restrictions occurred in four databases for articles published until July 2019. Eligibility criteria included prospective cohort studies, controlled clinical trials, and randomized clinical trials that evaluated the potential of allogeneic bone grafts in sensitized immune system in humans through immunological or biological analysis. The protocol number of this SR registered in PROSPERO is CDR42019135491. RESULTS: The search and selection process yielded eight prospective cohort studies published between 1984 and 2019. The percentage of patients' sensitization analyzed by human leukocyte antigens ranged from 21% to 67%, with a cumulative mean of 48 +/- 17.3%. Bone soluble protein analysis demonstrates the sensitization of 55% of patients after allograft bone grafts. Also, a high level of circulating cell-free DNA took place in the immediate postoperative period. CONCLUSION: Although studies report a low incidence of local complications, an average of 48% of the patients remain with the immune system sensitized after receiving allogeneic bone grafts. Future studies should better address the local and systemic consequences of such sensitization.