Transduction of a Positive Crossmatch into a Negative Crossmatch through Immunosuppressive Therapy

We report the case of a female prospective recipient of a living donor kidney transplantation where the crossmatch could be changed by means of immunosuppressive therapy. This is a first case-report demonstrating that caused by immunosuppressive treatment a positive x-match can be con-verted into a negative x-match successfully. After receiving an immunosuppressive therapy with 500 mg CellCept (MMF) twice a day for 6 months the x-match became negative as was checked 4 times subsequently. The patient’s sera prior to transplantatectomia showed after DTT-treatment (destruction of IgM antibodies) positive results in T-cell x-match, a reaction abviously caused by destruction of IgM anti-idiotypic antibodies. Anti-idiotypic antibodies (i.e. anti-antibodies) in most cases belong to the IgM-class and are known to suppress anti-HLA-antibodies biologically. Possibly, the graft was surviving for this long period (of about 12 years) because the anti-donor antibodies were sup-pressed by IgM anti-idiotypic antibodies of the recipient. However, after the CellCept therapy neither a positive CDC or Flow x-match result, nor a PRA with specific antibod-ies remained. This could be verified by monthly repeated x-matches between the recipient and the prospective living donor. Interestingly, after destruction of possible IgM-antibody specificities the phenomenon of the preectomia sera was observed again, i. e. due to destruction of IgM anti-idiotypic specificities the serum showed slightly positive x-match results with CD8 + donor T cells. It was demonstrated that immunosuppressive therapy with CellCept (MMF) made it possible to transfer a positive x-match into a negative current x-match. This transformation of the current x-match is caused by depression of the anti-body formation in the B-cell population as indicated by the company producing CellCept.