Good kidney transplant outcome in recipients with presensitization against HLA class II but not HLA class I.

It is a matter of debate whether pretransplant anti-human leukocyte antigen (HLA) class II antibodies contribute to the increased graft rejection rate found in presensitized recipients. We investigated the influence of preformed anti-HLA class II antibodies on graft survival in 5949 cadaver kidney transplants. Pretransplant recipient sera were tested in enzyme-linked immunosorbent assay (ELISA) for immunoglobulin (Ig)G-anti-HLA class I and IgG-anti-HLA class II antibodies. A total of 672 recipients with antibodies against HLA class II but not against HLA class I had a 3-year graft survival rate of 80 +/- 2%, identical to the 80 +/- 1% rate in 4561 recipients who were negative for anti-HLA class I and II (p = NS). Graft survival was significantly lower in 365 recipients who were positive for both anti-HLA class I and II (65 +/- 3%, p < 0.0001). Compatibility for HLA-A+B+DR influenced graft survival significantly in anti-HLA class I- and II-positive recipients (p = 0.0016), whereas no significant HLA effect was found in patients with antibodies directed against only class I or II. Surprisingly, not even incompatibility for HLA class II antigens of the DR locus caused a significant impairment of graft survival in anti-class II-positive recipients. We conclude that the risk associated with sensitization against HLA class II in the absence of sensitization against HLA class I is negligible.