Background: It is unclear whether detection of DSA by Luminex single antigen beads (LumSAg) accurately identifies those post-transplant alloantibody producing recipients at higher risk for eventual graft loss. Some studies suggest recipient donor-reactive antibodies may be adsorbed by the allograft and thus difficult to detect in the peripheral circulation. Also recipient antibody reactivity to LumSAg displaying donor HLA molecules may not represent true donor reactivity further complicates the issue. In this study we examined the clinical outcome of a cohort of recipients, all of whom had PRA detectable alloantibodies post-transplant, stratified on the basis of DSA status by LumSAg bead analysis and examined their clinical outcome. Results: From 4/2002 through 12/2009 there were 1,142 kidney transplants where post-transplant alloantibody testing was performed and of those, 451 had HLA class I or class II reactivity by multi-antigen flow bead PRA and were tested for DSA by LumSAg beads. 110/451 (24%) of these recipients had DSA confirmed by LumSAg analysis. Comparison of the DSA positive (n=110) versus the DSA negative (n=341) recipients revealed a similar incidence of re-transplantation (23.6% vs 22.3%, p=ns) and a lower percentage of pre-sensitized recipients (pre-transplant PRA> 6%, 39.1% vs 51.3%), but a higher percent of AA recipients (36.4% vs 24.9%, p=0.02), a higher incidence of previous acute rejection history (51.8% vs 25.6%, p<0.001), and higher incidence of biopsy confirmed AMR or mixed AMR and ACR (21.8% vs 12.6%, p=0.02). With the same time to antibody testing and follow up, the DSA negative group has an equally high rate of graft loss at 5 years (40% vs 27%, p=0.054) and at last follow up (50.1% vs 40%, p=0.064). By comparison, the graft loss rate for recipients without detectable alloantibodies post-transplant was 21.2% at 5 years and 31.2% at last follow up. Conclusions: The presence of circulating alloantibodies after kidney transplantation, when not donor specific as determined by luminex single antigen bead analysis, is not associated with a better graft survival. This suggests that such DSA identification by LumSAg offers no significant prognostic value over the simpler and cheaper multi-antigen and flow bead PRA screening methodologies.

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