Comparison of Single Antigen Bead-Based, Cell-Based, and Solid Phase-Based Crossmatch Methods.

AIM: Antibody assessment during pretransplantation term is important to detect donor specific antibodies. These donor-specific antibodies are determined by various crossmatch methods (flow cytometric [FCXM], complement-dependent cytotoxic [CDCXM], and Luminex [LMXM]). Recently, single antigen bead (SAB) assays have been used for the assessment of hypersensitized patients. The aim of this study was to compare sensitivity and specificity of the 3 crossmatch methods in reference to the SAB method. METHOD: In this study, 69 hypersensitized patients with high class I and/or class II panel reactive antibodies were tested using the flow cytometric SAB method. Serum samples were cross-matched by 3 crossmatch methods with the cells of a volunteer healthy individual, and the results were evaluated according to HLA and cross-reactive epitope groups (CREGs). RESULTS: Sensitivity was found to be better with T FCXM (0.91) and class I LMXM (0.87). Specificity of peripheral blood lymphocyte CDCXM method (1.0) was found to be better than the other 2 methods (0.33 and 0.57, respectively). Sensitivity of class II LMXM (0.88) was found to be better than the others (0.42 for B CDCXM and 0.82 for B FCXM, respectively). The specificity of the B CDCXM, B FCXM, and class II LMXM was similar (0.44, 0.44, and 0.33, respectively). CREGs results were similar to HLA results. CONCLUSION: Although CDCXM has high specificity for the detection of anti-HLA antibodies, it has low sensitivity. To increase sensitivity, FCXM or LMXM methods may be used with the CDCXM test. These results will be beneficial for laboratories and clinicians during graft survival and patient health assessment.

Investigation of Anti-HLA Antibodies of Highly Sensitized Patients by Single Antigen Bead and C1q Tests.

PURPOSE: The single antigen bead (SAB) test contributes to conventional cellular and solid phase crossmatch tests in renal transplantation. However, the determination of anti-HLA antibodies of the patients may not reflect the pathologic features of these antibodies. Highly sensitized patients produce antibodies against a number of HLAs; therefore, their transplantation chance decreases. In this study, we aimed to evaluate SAB and C1q test results of highly sensitized patients. METHOD: In this study, 33 end-stage renal failure patients with >80% panel reactive antibody were included. Of the patients, 58% (n = 19) were female, and 42% (n = 14) were male. The mean age was 46.2 ± 12.4. All of the serum samples were inactivated by heat before use. SAB and C1q tests were performed according to the manufacturer's instructions. RESULTS: We obtained statistically significant results between the positive bead counts and raw mean fluorescence intensity (MFI) values of 2 tests (P < .01 for class I and II). There was a statistically significant difference between the 2 tests in terms HLA-A, -C, -DR, and -DP MFI values, whereas HLA-B and -DQ MFI values were similar for the 2 tests. CONCLUSION: The difference of raw MFI values between the 2 tests may be due to the fact that the C1q test detects only IgG1 and IgG3 antibodies, whereas the SAB test can detect all IgG subtypes. We considered that anti-HLA-B and -DQ antibodies have high complement-fixing features; these antibodies should be investigated selectively due to the similarity of anti-HLA-B and -DQ antibody MFI values in the 2 tests.

A Comparative Study: Flow Cytometry, Complement-dependent Cytotoxicity, and Luminex Methods.

AIM: The cell-based flow cytometric and bead-based Luminex crossmatch methods have been used alongside the standard complement-dependent cytotoxic crossmatch (CDCXM) test to detect donor specific anti-HLA antibodies. In this study, it was aimed to compare flow cytometric crossmatch (FCXM), CDCXM, and Luminex donor-specific crossmatch (LM-XM) tests for pre-transplant assessment of patients who applied to Tepecik Education and Research Hospital for kidney transplantation from related or deceased donors. METHOD: HLA tissue typing of 1120 patients were tested using the sequence specific oligonucleotide probe method with low resolution. FCXM and LM-XM were performed according to the manufacturer's instructions. The CDCXM test was performed according to the standard procedure. The results were analyzed using SPSS version 21.0 software (IBM, Armonk, NY, United States). P < .05 was accepted as statistically significant. RESULTS: FCXM, CDCXM, and LM-XM tests were performed on 58.2% (n = 652), 91% (n = 1019), and 55.4% (n = 620) of 1120 patients. There were statistically significant differences between FCXM/CDCXM, LM-XM/CDCXM, and FCXM/LM-XM (P < .0001), although there was also a moderate correlation between them (for class I, r = .599, r = .693, and r = .507; for class II, r = .546, r = .471, and r = .495, respectively). The results obtained according to donor type were compatible with the total study group. CONCLUSION: The utilization of FCXM and/or LM-XM tests together with the CDCXM method before kidney transplantations from related and/or deceased donor may facilitate the determination of target cells of donor-specific antibodies or their antibody class, which may increase the success of transplantation.