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%.

Role of major histocompatibility complex and ethnicity in acute renal graft rejection.

BACKGROUND: The major histocompatibility complex (MHC) plays a main role in antigen presentation. Class I, II, and III genes form defined "blocks" of conserved DNA sequences (conserved extended haplotypes) that are useful to follow the ancestry of a population. Each variant encodes a specific peptide that determines a particular individual's immune response. In addition, differential expression of HLA antigens in certain physiological and pathological conditions may participate in the pathogenesis of allograft rejection versus tolerance. OBJECTIVES: The aim of this study was to determine whether the specific HLA ancestry was associated with acute renal graft rejection among the Mexican mestizo population. MATERIALS AND METHODS: We studied 544 Mexican mestizo renal donors and their respective recipients for their serologically determined HLA and based on antigens haplotype assignments. The acute rejection group was compared with the nonrejection group among donors and recipients, correspondingly. RESULTS: Frequent Mexican alleles were observed in this study. Moreover, HLA-B*61/-DR*04, HLA-A*35/-DR*06 (Amerindian ancestry), HLA-A*68/-DR*01, HLA-A*28/-B*65/-DR*01 (African ancestry), and HLA-A*33/-B*65 (Caucasian ancestry) in donors were associated with acute renal graft rejection episodes. CONCLUSION: Knowing the ancestry of a donor's HLA molecules may help to individualize immunosuppressive therapy for posttransplant surveillance, because they may be more membrane-exposed in parenchymal cells, making them more susceptible of being recognized by the recipient's immune system.

HLA class I and class II alleles and haplotypes in Mexican mestizos established from serological typing of 50 families.

We describe new information on the frequency and association of class II antigens (HLA-DR and HLA-DQ) of the major histocompatibility complex (MHC) in Mexicans. The study includes HLA-B typing and its association with the HLA-DR antigens determined in 50 families, which included 100 individuals. This family study allowed the establishment of the precise composition of the 200 HLA haplotypes, which cannot be obtained from unrelated individuals. The predominant antigens in decreasing order of frequency were B35, B39, and B61 at the B locus; DR4, DR5, and DR8 at the DR locus; and DQ3 at the DQ locus. The most common HLA-B,HLA-DR haplotype (considering broad specificities) was B16,DR4, with a frequency of 8.0%. Five HLA-B,HLA-DR haplotypes showed significant delta values (observed vs. expected frequencies) after correcting for the number of comparisons. On the other hand, the most common HLA-DR,HLA-DQ haplotypes were DR4,DQ3 and DR5,DQ3 with a frequency higher than 10%. Ten of the 17 HLA-DR,HLA-DQ haplotypes had significant postcorrection delta values.