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THE FREQUENCY OF DE NOVO HLA ANTIBODY AT SERIAL TIME POINTS POST RENAL TRANSPLANT.
Peter Nickerson, MD, Denise Pochinco, RT, Iga Dembinski, RT, Kendra Hacking, RT, Willie Laidlaw, RT, Martin Karpinski, MD, John Jeffery, MD and David Rush, MD. Winnipeg MB, Canada, Canadian Blood Services, R3E 3R4, Immunogenetics Laboratory and Winnipeg MB, Canada, University of Manitoba, R3E 3R4, Department of Medicine.

Studies that report HLA antibody post-transplant have examined for the presence of antibody at random time points and correlated their presence with long-term outcomes (i.e. chronic rejection). In the current study we determined in 88 primary renal transplant patients who have at least 5 year follow-up, the incidence of de novo HLA antibody in serial serum samples at 1, 2, 3, 6, 12 and 24 months post-transplant. Pre-transplant all renal transplant recipients had been assessed for HLA antibody by both flow cross-match and FlowPRA microbeads and were found to be unsensitized.
The following table reports the percentage of patients with detectable HLA antibody at the specified time point post-transplant.

De Novo HLA Antibodies
HLA Ab1 mo2 mo3 mo6mo12mo24mo
Class I9%7%7%5%15%11%
Class II2%8%7%6%12%9%


De novo Class I antibodies at 6 months correlated with the development of chronic rejection by 5 years post-transplant. In comparison it was not until 24 months that de novo Class II antibodies correlated with the development of chronic rejection in the first 5 years post-transplant.
De novo HLA antibody is infrequent post-transplant, however when present as early as 6 months it is strongly associated with the subsequent development of chronic rejection. The delay between the initial presence of de novo HLA antibody and the subsequent development of chronic rejection suggest a potential window of opportunity to test novel therapeutic approaches to prevent graft loss to chronic rejection.