Effect of implementing anti-HLA antibody detection by Luminex in the kidney transplant program in Chile.

The development of new highly sensitive, specific technologies to detect HLA antibodies has allowed a better definition of the profile of non-permitted antigens for patients awaiting kidney transplantation. The use of calculated or virtual panel reactive antibodies (CPRA or vPRA) seeks to improve the prediction of positive crossmatches (XM), but increases the proportion of sensitized patients on the waiting list. In 2008-2009, we implemented detection of antibodies using Luminex technology and applied vPRA since 2009. The objective of this study was to evaluate the impact of these innovations in defecting patient sensitization on kidney transplant waiting lists for deceased donors and among transplanted patients. We analyzed the waiting list for 2007 through 2009 and the first semester of 2010, including the patients transplanted in these periods and the XM with deceased donors. We observed an increase in the mean peak PRA of transplanted patients from 7.2% in 2007 to 17.1% in 2010 (P = .001), and in the proportion of patients transplanted with a peak PRA > 50% from 2.8% in 2007 to 15.7% in 2010 (P = .0001), with no increase in the proportion of this population on the waiting lists. There was a concurrent decrease in positive XM among patients with a peak PRA > 50%. The use of vPRA and Luminex permitted a greater number of transplants of patients with peak PRA > 50% and was a good predictor of a positive XM.

Evaluation of the stages involved in cold ischemia time in renal transplants in Chile.

INTRODUCTION: Cold ischemia time (CIT) is one of the factors that determine the evolution of a renal transplant; taking measures to reduce this time requires knowledge of its stages. The objective of this study was to evaluate the times in the stages that determine CIT in renal transplants. METHODS: We analyzed 108 donors and 201 kidney transplantations performed in Chile in 2008, establishing the CIT for the kidney transplanted by the center that extracted the kidneys (local kidney) and for the kidney transplanted in another center (shared kidney). RESULTS: Average CIT was 18.8 hours: namely, 16.9 hours for local and 20.2 hours for shared kidneys (P = .0001484). CIT for cases in which samples were sent to histocompatibility laboratory prior to nephrectomy was 7.3 hours less than for those sent postnephrectomy. The mean time between the allocation of the kidney and the transplant was 7.3 hours; 5.6 hours for local kidneys and 8.4 hours for shared kidneys (P = .000007124). CONCLUSION: We identified the stages at which intervention is possible to reduce the CIT, mainly for shared kidneys. All involved parties should make an effort to reduce this time.

Early and late humoral rejection: a clinicopathologic entity in two times.

Humoral rejection is an important cause of early and late graft loss. The late variant is difficult to diagnose and treat. There is a close correlation between sclerosing nephropathy and anti-HLA antibodies. We analyzed 113 renal allograft recipients between August 2004 and April 2007. Acute humoral rejection was defined as acute graft dysfunction in presence of donor-specific antibodies (DSA) detected by flow panel reactive antibodies (PRA) and/or C4d positive pericapilary tubules (PTC) detected histopathologically by immunofluorescent or immunoperoxidase at less than 3 months postransplantation. Late humoral rejection was defined as dysfunction occurring after 3 months postransplantation with histopathologic glomerulopathy or vasculopathy and positive C4d PTC. We included all patients who were diagnosed with early or late graft dysfunction and underwent biopsy, all of which were examined for C4d. Four patients had acute humoral rejection treated with IVIG or plasmapheresis. The patient and graft survivals were 100% and serum creatinine averaged 1.7 mg/dL. Three recipients experienced late humoral rejection at 3 to 10 years posttransplantation All received high-dose IVIG; one also was treated with thymoglobulin. Immunosuppression was switched to tacrolimus, mycophenolate mofetil, and steroids. Only one patient recovered renal function; the others returned to dialysis. Among seven patients only one had an actual PRA (>20%) and three showed 10% to 20%. However, six had a positive historical PRA of 10% to 50%. In conclusion, Recognition of acute humoral rejection has contributed to graft rescue by controlling alloantibody production through new specific immunosuppressive therapies in contrast with the clinical response to acute therapy, treatment of a chronic entity has shown poor outcomes, probably because antibody mediated chronic graft damage is already present when the late diagnosis is established by biopsy.