Effect of MDR1 polymorphisms on the blood concentrations of tacrolimus in Turkish renal transplant patients.

BACKGROUND: Tacrolimus, a calcineurin inhibitör, is prescribed to prevent allograft rejection in renal transplantation. Tacrolimus not only has a narrow therapeutic index, but also shows significant interindividual differences. The absorption and metabolism of this drug are affected by multidrug resistance (MDR) 1 gene polymorphisms that correlated with single-nucleotide polymorphisms (SNPs) affecting in vivo P-glycoprotein activity. This study investigated associations of MDR1 gene C3435T polymorphism with tacrolimus blood concentrations and dose requirements as well as acute rejection episodes among Turkish renal transplant patients. METHODS: One hundred living-donor transplant recipients and 150 healthy control subjects underwent C3435T genotyping using polymerase chain reaction-restriction fragment length polymorphism. Blood concentrations of tacrolimus were determined with the cloned enzyme donor immunoassay. RESULTS: The CC, CT, and TT genotype frequencies among patients were, respectively, 44.0%, 33.0%, and 23.0% versus 36.7%, 43.3%, and 20.0% among control subjects. There was no significant difference between (P = .061; P = .102; P = .211; respectively). The ratio of blood concentration to dose of tacrolimus for patients with mutant homozygous 3435 TT genotype was higher than that of wild-type 3435 CC genotype homozygous individuals. The doses for these patients were lower at 1, 3, and 12 months (P = .048; P = .03; P = .041, respectively). There were no significant differences between the groups regarding coprescription of drugs that affect tacrolimus concentrations, such as diltiazem. Acute rejection episodes were not associated with the CC vs CT or TT genotypes: odds ratio (OR), 0.517 (95% confidence interval [CI], 0.190-1.407; P = .192); OR 1.558 (95% CI, 0.587-4.136; P = .372); OR 1.346; (95% CI, 0.456-3.968; P = .590), respectively. CONCLUSIONS: Determination of MDR1 polymorphism may help to achieve target of tacrolimus blood concentrations.

Flow cytometric evaluation of pregnancy-induced anti-donor immunization.

BACKGROUND: Living donor kidneys from spouses and children (from offspring to parents) are currently considered to be important organ sources. However, pregnancy-induced alloimmunization may provoke acute rejection episodes after kidney transplantation. being flow cytometry cross-match (FCXM) we studied donor-specific antibodies (DSAs) in the sera of recipients planned for living kidney transplantation from their spouse or children. When the FCXM was positive, we confirmed the existence of anti-human leukocyte antigen (HLA) antibodies using flow cytometry panel-reactive antibody (flow-PRA). PATIENTS AND METHODS: Between March 2005 and November 2010, we tested 85 pretransplantation sera from renal transplant recipients for DSAs. The recipients included 37 wives (group I) and 48 husbands (group II). FCXM-positive sera were tested using a flow-PRA screening method using HLA class I and class II antigen-coated beads. The mean recipient age was 48.1 ± 9.8 (range, 28-69) years and the mean donor age was 45.1 ± 11.1 (range, 23-69 years). RESULTS: Among group I were 18 (48.6%) FCXM-positive cross-matches; for group II, 5 (10.4%) cases (P = .001). Sensitized patients were 37.9% FCXM-positive, whereas nonsensitized patients were 3.7% positive (P = .001). FCXM-positive patients were re-evaluated for anti-HLA antibodies using flow-PRA. Seventeen of 18 group I tests (94.4%) were FCXM-positive, whereas 3 of 5 (60%) were positive among group II. CONCLUSIONS: We concluded that flow cytometry-based cross-match and PRA techniques can be used to detect anti-HLA antibodies using spousal or children donors for kidney transplantation.

Flow cytometric crossmatching and panel-reactive antibodies in chronic renal failure patients.

AIM: Anti-donor antibodies, denoted as "panel-reactive antibodies" (PRAs), are one of the most important factors influencing graft survival after renal transplantation. PRA is generally analyzed with enzyme-linked immunosorbent assay or flow cytometry (FC), which identify the HLA antigen specific for the preformed antibody. PATIENTS AND METHODS: We tested 66 patients for FC crossmatch (FCXM) when they were called for cadaveric renal transplantation. Thirty of 66 patients were FCXM-positive; 36 were FCXM-negative. Among the FCXM positive crossmatches, 21 were T- and B-cell positive; seven B positive; and two T positive. The HLA antibodies in the sera of FCXM-positive patients were reanalyzed using flow-PRA. RESULTS: We detected HLA antibodies in 28/66 sera with flow PRA. The sera of 16/21 T-/B-, FCXM-positive patients contained both class I and II anti-HLA antibodies, five had only class I anti-HLA antibodies. One out of seven B-cell FCXM-positive patients had class I and class II anti-HLA antibodies, three, class I and 1 class II anti-HLA antibodies; the other two were negative. Class I and class II HLA antibodies were observed in two T-cell FCXM-positive patients. Four of 36 patients who were FCXM-negative were flow PRA positive: one had both class I and class II HLA antibodies and three, only class I HLA antibody. The comparison of FCXM and flow PRA results was significant (P = .001). CONCLUSION: FCXM results may be confirmed by flow PRA tests, an important method to differentiate HLA versus non-HLA antibodies.