A Case Study on Evaluation of the Correlation between Crossmatch Methods and Single Antigen Bead Test

Research Article

Austin J Nephrol Hypertens. 2015; 2(4): 1045.

A Case Study on Evaluation of the Correlation between Crossmatch Methods and Single Antigen Bead Test

Gulec D*, Kilicaslan Ayna T, Soyoz M, Kiliçoglu M and Pirim I

Izmir Tepecik Education and Research Hospital Tissue Typing Lab, Turkey

*Corresponding author: Derya Gulec, Izmir Tepecik Education and Research Hospital Tissue Typing Lab, 35120 Yenisehir/Izmir-Turkey

Received: August 24, 2015; Accepted: October 15, 2015; Published: October 20, 2015


Introduction: The chance for transplantation from a crossmatch (XM) negative donor is low in hypersensitized patients. Single Antigen Bead (SAB) assay is one of the current tests that determine HLA antigens which may be accepted by the patients. In this case report, donor specific antibodies were investigated by flow cytometric SAB in the sera of two patients. Besides, the correlation between CDCXM (Complement-dependent cytotoxic crossmatch), FCXM (Flow cytometric crossmatch) and Luminex XM was also compared.

Methods and Materials: Flow cytometric SAB was performed by using sera from two hypersensitized male patients. Furthermore, the two sera were also tested by CDCXM, FCXM and Luminex XM tests using the cells from a healthy volunteer.

Results: CDCXM was found negative while FCXM and Luminex XM tests were positive for the first patient. All of the XM tests were found positive for the second patient. Besides, CDCXM and FCXM results were highly positive for the second patient with high MFI values in Luminex XM. As a result of flow cytometric SAB test, it was observed that acceptable HLA antigen number was lower in the patient with high MFI value.

Conclusion: SAB Assay determines the acceptable antigens that cannot be identified by the other XM techniques used for the determination of DSAs in immunology laboratories. This provides the patients advantages for graft survival and organ sharing. In addition, a second crossmatch test beside CDCXM test helps the clinical more for the identification of antibodies in low density.

Keywords: Flow cytometry-Single Antigen Bead (FC-SAB); Virtual crossmatch


The presence of donor specific antibody (DSA) against human leukocyte antigens (HLAs) is the most significant reason of early kidney allograft rejection and graft failure. There are various techniques that can be used in determination of DSAs in graft waiting patient sera. Flow cytometric crossmatch (FCXM), can detect all of IgG types (IgG1, IgG2, IgG3, IgG4) besides the antibodies in low concentration that cannot be detected by CDC crossmatch (CDCXM). This allows FCXM be 10-100 times more sensitive than CDCXM test [1-3]. However, the specify of this test is lower, although it is more sensitive than CDCXM test. Luminex XM technology solid phase assay, can detect properly class I and II anti-HLA antibodies below the level that cannot be identified by CDCXM and FCXM. In this system, micro-beads covered by HLA antigens are used for the identification of anti-HLA antibodies in flow analyzer. Unlike FCXM, this system detects only anti-HLA antibodies (not non-HLA antibodies). Luminex technique has more sensitivity and specify than other cellular methods [4-6]. Acceptable and unacceptable HLA antigens can be detected by using the beads covered by only one recombinant HLA molecules (Single Antigen Bead: SAB). Thus, SAB method is also termed as virtual XM.

In this study, anti-HLA antibodies of two patients with >80% PRA result were detected by FC-SAB and the correlation of these results with three different crossmatch methods was investigated.

Materials and Methods

Two patients were accepted to our laboratory for their panel reactive antibody screening. The patients were 41 and 39 years-old, both of them were male and transplanted from a deceased donor in 2008 and 1999, respectively. However, the transplanted kidneys were explanted approximately 3 years after the transplantation. Besides transplantation, they had 2 and 5 unit blood transfusion after transplantation, respectively. The HLA types of deceased donors were not available from hospital registries. The tissue typings of the patients were performed by low-resolution PCR-SSO (Polymerase Chain Reaction-Sequence Specific Oligonucleotide) method (Lifecodes HLA Typing Kit Immucor Gamma, USA) and found as A*02 A*68 B*53 B*27 DRB1*11 DRB1*11, A*01 A*03 B*07 B*60 DRB1*10 DRB1*12, respectively.

The IgG antibodies produced against class I and II molecules were found 100% positive by Luminex PRA screening (LMX-Life Codes Life Screen Deluxe Kit, Immucor Gamma, USA) and identification (LM1, LM2Q- IDv2 Kit, Immucor Gamma, USA) tests during their last application to our laboratory.

The patients’ sera were tested by flow cytometry technique (FL1HD and FL2HD; One Lambda, Germany) in which beads that are covered by a single antigen are used in order to detect the most common HLA antigens and which allows virtual crossmatch. The results were evaluated by flow cytometry instrument (BD Facscalibur, USA). The acceptable HLA antigens were shown in Table 1.

Citation: Gulec D, Kilicaslan Ayna T, Soyoz M, Kiliçoglu M and Pirim I. A Case Study on Evaluation of the Correlation between Crossmatch Methods and Single Antigen Bead Test. Austin J Nephrol Hypertens. 2015; 2(4): 1045. ISSN : 2381-8964