Probability of deceased donor kidney transplantation based on % PRA.

UNLABELLED: Sensitization to HLA antigens creates an obstacle for the accessibility and success of kidney transplantation (KT). Highly sensitized patients have longer waiting times and some may never receive a KT. AIM: To determine the probability of patients on the deceased donor (DD) waiting list to receive a KT based on the panel reactive antibody percentage (% PRA) in our center. METHODS: The DD waiting list from our institution was analyzed from 01/05 to 08/12 documenting the clinical variables from donor and potential recipients (ABO blood group), lymphocyte cross-match [CxM (CDC-AHG)] results, highest % PRA determination, and time on the waiting list. The patients were classified into 4 groups based on the % PRA: 0%, 1-19%, 20-79% and 80-100%. The data was analyzed using odds ratio and logistic regression (significant p<0.05). RESULTS: 58 DD (F:M 34:24, ABO group O=35, A=13, B=10) and 179 potential recipients were analyzed (F:M 98:81, ABO group O=127, A=33, B=19, participating 4.2 ± 3.8 times with different donors to receive KT). The mean PRA for the whole group was 22 ± 32%, median [md] 0 (0-98). A total of 100 patients received KT (mean waiting time 2.2 ± 1.7 years, 12 days-7 years) and their mean % PRA was 11.6 ± 24, md 0 (0-94) vs. 31.4 ± 37 md 8.5 (0-98) in those who have not received a KT. An association between the % PRA group and KT (p<0.003) was observed. The probability of receiving KT with a 0% PRA vs. >0% was higher (OR 2.12, 1.17-3.84). There was no difference between the 0% vs. 1-19% group (OR 1); differences were observed between 0% vs. 20-79% (OR 2.5, 1.18-5.3) and 0% vs. 80-100% (OR 5, 1.67-14.9). For every percent increase in the PRA above 20%, the risk of not receiving a KT increased by 5% (1-9, p<0.01). CONCLUSIONS: The probability of receiving a DD kidney transplant is inversely related to the % PRA although a higher risk for not receiving a KT becomes evident with a PRA >20%.

Time of occurrence of kidney acute antibody-mediated allograft rejection/acute cellular rejection and cell senescence: implications for function outcome.

BACKGROUND: Late versus early acute antibody-mediated rejection (AAMR) or acute cellular rejection (ACR) episodes are associated with poorer kidney function and graft survival. We explored whether cell senescence upon detection of AAMR ± ACR contributes to these results. METHODS: We reviewed the renal transplant database of 2 Institutions. Biopsies performed for acute graft dysfunction from January 2000 to March 2007 were analyzed for morphological criteria of AAMR with or without ACR (n = 17 from 17 patients). Immunoperoxidase staining for p16(INK4B) was performed on the remaining paraffin-embedded tissue in 9 of 17 cases. The average number of positive cells/high power field (HPF) was calculated in every case. Cases with rejection were grouped according to the time of presentation: early (<3 months n = 8) versus late (>3 months; n = 9). Graft function was obtained using the Modification of Diet in Renal Disease (mDRD) glomerular filtration rate estimate (eGFR) before, during rejection, and at the last visit, to calculate ΔeGFR. RESULTS: Nuclear expression of p16(INK4B) was 12.2 ± 11.3 cells/HPF in 4 of 8 biopsies performed at a median of 23 (range = 4-80) days (early AAMR ± ACR), and 59.8 ± 51.3 cells/HPF in 5 of 9 biopsies performed at a median of 1171 (range = 279-3210) days (late AAMR ± ACR). eGFR before rejection was 48.5 ± 7.6 mL/min, and 43.7 ± 4.3 mL/min for early and late rejection episodes, respectively (P = not significant [NS]). ΔeGFR of 12.5 ± 25.9 mL/min (early rejection), and -13.7 ± -12.3 mL/min (late rejection), versus last follow-up visit (P = .02) occurred at a median of 143.9 ± 94.1 and 69.6 ± 35.1 weeks after the rejection episodes, respectively. CONCLUSIONS: Even though the number of biopsies analyzed for p16(INK4a) was small, it was evident that the number of cells expressing this marker of senescence was higher among biopsy specimens obtained with late rejection episodes. This finding suggests the presence of injuries prior to the rejection episode. The significantly lower eGFR at last follow-up in the late rejection group may translate to a reduced capacity of the repair process to sustain nephron function.