Immunological responses to bone soluble proteins in recipients of bone allografts

The significance of an immune response in complications of bone allograft procedures is not well understood. This study evaluates the immunological reaction to bone allografts in either cortical or cancellous form. Serological responses from osteoarthritis (OA) patients and normal individuals to soluble proteins extracted from allografts were assessed using Western blotting and ELISA techniques. A large number of patients expressed antibodies to bone proteins extracted from the washed bone as compared with normal controls. Antibodies were present in patients without the use of bone allografts, indicating that OA patients develop antibodies to bone soluble proteins. However, patients receiving allografts exhibited an increased immune reactivity against multiple bone proteins when compared with non-grafted patients. Protein characterization of the immunoreactive proteins revealed that the majority of antigenic targets were fragments of various collagen molecules. The data suggests that OA patients develop antibodies to bone soluble proteins prior to surgery, and these antibodies increase after revision surgery utilizing bone allografts. These findings support the implications that various collagen molecules as well as their degraded fragments represent potential immunogenic proteins within bone allografts. The removal of these antigenic proteins from the allografts prior to surgery may alleviate this immunological reactivity and improve graft outcome.