De Novo Anti-HLA Sensitization in Pediatric Kidney Transplant Recipients.

Abstract

Introduction: Anti-HLA de novo sensitization may have a poor impact on graft survival as it is usually related to the presence of acute or chronic Humoral Rejection, both events being a known cause of graft loss. Anti-HLA antibodies screening may allow us to identify a subgroup of patients on special risk of immunological adverse events. Methods: The results of a periodic anti-HLA antibody (HLA Ab) screening (Luminex® technique), performed from January 2010 since January 2013, in a cohort of 38 pediatric (1-18 years old) kidney transplant receptors of a single center are analyzed. The mean post-transplant follow-up time is 79.2 (27.3-165.1) months. Patients with an anti-HLA positive screening have been studied with Single Antigen (SAg) technique. The HLA Ab prevalence and specificities and their relationship with: donor type, previous kidney grafts, time since transplant, graft rejection, HLA mismatches, immunosuppressive (IS) medication and Tacrolimus trough blood levels, are studied. The relationship between HLA sensitization and graft outcome by Glomerular Filtration Rate (GFR) and Proteinuria/creatinuria ratio measurements at last follow-up are also analyzed. Results: An anti-HLA sensitization prevalence of 34.2% (13/38 receptors) is found in our studied population. Single Antigen technique concluded that in 10 receptors the HLA antibodies found were Donor Specific Antibodies (DSA) against the actual graft while in 3 cases they were DSA against a previous donor. At 15.9 (2.4-27) months of follow-up after the diagnosis of sensitization no impact on graft survival or GFR is found on these 10 receptors, but a significant presence of proteinuria and Hypertension is observed. HLA sensitization is more frequent on receptors with long term transplant (p 0.016) and on those with low Tacrolimus trough blood levels (p 0.024). Double IS therapy is more frequent in HLA sensitized receptors than triple IS therapy, but no statistical significance on the analysis isfound (p 0.062). Conclusions: HLA sensitization is present in one third of our pediatric kidney transplant receptors and is related to anticalcineurin minimization strategies. At short term follow-up no graft losses are found but proteinuria and hypertension are more prevalent on these receptors, probably being a first marker of subjacent renal damage.