Renal transplantation despite a positive antiglobulin crossmatch with and without prophylactic OKT3

The antiglobulin crossmatch (AGXM) is a sensitive technique employed by many transplant centers to enhance detection of preformed antibody to donor antigens that may cause hyperacute rejection. However, positive AGXM may detect irrelevant or very low titers of antiHLA antibody precluding transplantation in suitable recipients. To investigate the significance of a positive AGXM, cadaveric renal transplantation was carried out despite a weakly positive AGXM (defined as cell killing above background but not >20%) in 48 recipients. In an initial group (n=10), maintained on triple therapy (cyclosporine, azathioprine, and prednisone), accelerated acute rejection occurred in 4 recipients and 3 grafts were lost. A subsequent group (n=38) was treated with a prophylactic course of OKT3 then triple therapy. There were no episodes of accelerated acute rejection (PcO.Ol) although clinical hyperacute rejection claimed one graft and the incidence of delayed graft function was high (75%). The prophylactic OKT3 group had a reduced incidence of acute rejection (0.5 versus 1.0) per recipient and the onset of first episodes was delayed (mean onset: 13 versus 35 days after transplantation). One year actuarial primary graft survival was 88% in the prophylactic OKT3 group as compared with only 50% in the initial group. The outcome in the positive AGXM group was similar to a concurrent group (n=32) with a negative AGXM and immediate graft function. On the other hand, the subset of positive AGXM regraft recipients treated with prophylactic OKT3 fared poorly, with a 36% (4/11) incidence of primary nonfunction. In summary, a positive AGXM, as defined in this report, is not a contraindication to primary renal transplantation—in fact, the use of the AGXM will identify recipients that would benefit from prophylactic OKT3.