Background: Whilst preformed [PF] anti-HLA A, B, DR and DQ donor specific antibodies [DSAbs] are associated with poorer allograft outcomes secondary to antibody mediated injury, there are only a few case reports describing the clinical significance of PF anti-HLA DP DSAbs. In this study we describe the clinical importance of PF isolated anti DP DSAbs.

Results: 1273 CDC/FCXM negative renal transplant recipients [mean follow up 4.46 ± 2.50 yrs] receiving a steroid sparing, tacrolimus based maintenance regimen with monoclonal antibody induction were studied. 98 patients had ≥1 preformed DSAbs and 9/98 [9.2%] had an isolated PF DP DSAb. Of these 9 patients, 3/9 were sensitised via previous transplantation, 4/9 pregnancy, 2/9 transfusion and 1 unknown. DP4 was the commonest loci seen, with 4/9 having DP4 DSAb, 2/9 DP1, 2/9 DP3 and 1/9 DP17. The mean MFI at the time of transplant was 2608 ± 1039. Allograft outcomes were compared between patients with PF DP DSAb, DSAb negative sensitised patients (S) and non-sensitised patients (NS) and the results shown in the table below. Patients with DP DSAb had increased risk of graft loss, rejection [AMR and ACR] and TG. PF DP DSAbs are rare but when present are associated with inferior allograft outcomes as displayed in table 1.

Conclusion: Donors for patients with known PF DP HLA Abs should be typed for DP as these recipients are at higher immunological risk if the antibody is donor specific and may benefit from increased surveillance and immunosuppression.

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