Kidney transplantation in patients with antibodies against donor HLA class II.

The immunologic risk associated with donor-specific antibodies (DSA) against Class II human leukocyte antigens (HLA) in kidney transplant (KTx) recipients is unclear. The aim of this study was to determine the outcome of KTx when DSA was detected only against HLA Class II. To isolate the impact of anti-Class II DSA, we retrospectively analyzed 12 KTx recipients who at baseline had a positive B-cell flow cytometric crossmatch (FXM) and a negative T-cell FXM. Using alloantibody specification analysis, 58.3% (7/12) had DSA against donor Class II and 41.7% had no demonstrable DSA. Biopsy-proven AMR occurred in 57% (4/7) in the Class II(+) group and 0% in the Class II(-) group (p > 0.05). Peritubular capillaries stained positive for C4d in 86% (6/7) of the Class II(+) patients and in 40% (2/5) of the Class II(-) patients (p > 0.05). One patient in the Class II(+) group lost their graft at 3 months to accelerated transplant glomerulopathy, while all other grafts were functioning 3-37 months posttransplant despite the persistence of anti-Class II DSA. We conclude that KTx recipients with clearly defined anti-Class II DSA are at risk for humoral rejection suggesting that desensitization and/or close posttransplant monitoring may be needed to prevent AMR.

Antagonists of cyclic nucleotide phosphodiesterase (PDE) isozymes PDE 3 and PDE 4 suppress lymphoblastic response to HLA class II alloantigens: a potential novel approach to preventing allograft rejection?

As a potential novel approach to preventing renal allograft rejection, we investigated whether the proliferative response of lymphocytes to mismatched HLA class II antigens in mixed lymphocytic culture (MLC) can be suppressed by antagonists of cyclic nucleotide phosphodiesterase (PDE) isozymes. Cilostamide, an antagonist of isozyme PDE3 and, to an even greater extent, in combination with rolipram, an antagonist of isozyme PDE4, markedly suppressed (delta = -60%; p < 0.01) the mitogenic proliferative response of lymphocytes in MLC to HLA-DR alloantigens from unrelated donors. These observations suggest that the selective PDE isozyme antagonists might have potential as novel drugs in "signal transduction-targeted" pharmacotherapy of renal transplant rejection.

HLA antibody screening: comparison of a solid phase enzyme-linked immunoassay with antiglobulin-augmented lymphocytotoxicity.

BACKGROUND: IgG antibodies to HLA class I antigens can cause hyperacute rejection of renal allografts. Screening of sera from such transplant candidates is laborious, time-consuming, and expensive when performed by sensitive antihuman globulin-augmented lymphocytotoxicity (AHG-CDC). METHODS: Because 60-70% of our transplant screens are negative, we evaluated a solid phase enzyme-linked method (EIA) as a potential prescreen by parallel testing 215 sera by AHG-CDC and by EIA. This EIA method is designed to detect only IgG antibodies, and all positive AHG-CDC sera were retested after dithiothreitol treatment. RESULTS: There was 96.2% concordance between the tests for IgG antibodies. Seven sera (3.25%) were positive by EIA alone, and one (0.46%) was negative by EIA alone. The EIA method was also less costly ($15.00 versus $105.00) and less time consuming (hours versus days) than AHG-CDC panel testing for large numbers of sera. CONCLUSIONS: We conclude that this EIA method is simple, sensitive, objective, and cost effective as a prescreen for HLA class I antibodies.