No Effect of HLA Antibodies Detected by Luminex Based Single Antigen Tests Only, on Kidney Survival, Graft Function or Acute Rejection

Abstract

Introduction: There are conflicting reports about the risk of kidney transplants performed in the presence of donor specific HLA Antibodies (Abs) that are only identified with Luminex single antigen testing. Furthermore there are reports that other non-DSA HLA Abs might also carry some additional risk. Our experience has shown in the past that such transplants can be performed safely. Aim and Methods: This was a prospective study to investigate in a series of consecutive kidney transplant patients performed in the knowledge of a negative crossmatch if the presence of HLA Abs that were Donor specific or otherwise resulted to an increased incidence of graft failure, acute rejection or to a worse kidney function as measured by creatinine and eGFR. Pre-transplant sera from 343 adult renal transplant recipients transplanted during a 45 month period were investigated for the presence of antibodies to HLA using Luminex LABScreen Mixed. Mixed positive sera were further tested by LABScreen Single Antigen for determination of HLA specificity. There was a minimum follow up of three years. A significant number of those patients did not receive any antibody induction. Results: There were 213 patients with Luminex only Abs with a level over 500 out of which 85 had DSAs. There were 28 patients with DSA level over 2000 (9 class I and 19 class II) and 9 with level over 5000 all class II. There was no impact of the Ab presence (DSA or not) or the antibody level (as measured by the Single Antigen beads) on the kidney graft survival up to 3 years. Furthermore the rejection rate including borderline rejection was no different between the positive and the negative DSA groups either class I (22% in patients with DSA class I over 2000 vs 28% on those without) or class II (36% in patients with DSA class II over 2000 vs 27% on those without) and at any antibody level. The 6 months, 1 year and 2 years creatinine and creatinine clearance were similar between the positive and negative DSA groups again at any level of sensitisation. Conclusion:Transplantation in the presence of Luminexonly HLA Abs, in the absence of a positive crossmatch, is safe, resulting in equivalent graft survival, kidney function and even rejection rates up to 3 years post transplant. This is the largest prospective study of single antigen testing in kidney transplantation with a complete 3 year follow up.