Immune response to fresh meniscal allografts in mice

To date, no study of allogeneic meniscal transplantation has investigated both the host cellular immune response and the humoral immune response. Using inbred mice, we examined cellular and humoral immunity to meniscal allografts through the mixed lymphocyte culture reaction and a complement-dependent cytotoxicity test. We also examined the histology of an allogeneic meniscus transplanted subcutaneously. The stimulation index of the mixed lymphocyte culture seen after placing fresh meniscal allografts subcutaneously was not significantly higher than when isograft controls were similarly placed. Following placement of the allografts, no specific antibodies were detected in serum throughout the 24-week period after grafting. Although viable fibrochondrocytes in the allogeneic meniscus decreased in number and lymphocyte infiltration around the allogeneic meniscus was noted at Week 2, no remarkable infiltration of lymphocytes into the meniscus was observed. These results indicate that in our experimental mouse model, a fresh meniscus apparently is not sufficiently immunogenic to induce a systemic reaction. Our results suggest that a fresh allogeneic meniscus can be transplanted without any special treatment to decrease its immunogenicity.