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

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.