P137 The importance of re-evaluating the HLA antibody profile and auto-antibody status when the flow cytometry crossmatch result is not as expected

Autor: Blanca Ponce-Ngo, Jiali Shen, Angelo N. Arnold, Marzanna Krolik, Scott Hodgson
Rok vydání: 2016
Předmět:
Zdroj: Human Immunology. 77:138
ISSN: 0198-8859
DOI: 10.1016/j.humimm.2016.07.202
Popis: Aim The flow cytometry crossmatch (FCXM) is a decision-maker for organ transplantation. A positive FCXM against T-Cells and/or B-Cells increases the risk for rejection. For this reason, a “positive” FCXM often eliminates the patient from consideration for transplant. The listing of unacceptable HLA (UAgs) reduces the probability for an unexpected positive FCXM. The FCXM and processes to define UAgs are not perfect. Herein, we provide three cases in which the transplant decision changes with additional laboratory testing and the way the FCXM is reported. Methods A standard three-color FCXM uses PerCP-CD3 and PE-CD19 (BD Bioscience) to label T- and B-Cells, respectively, and FITC- Fab’2 goat anti-human IgG (Jackson Lab) to detect antibody binding. A median channel difference (MCD) of 35 for T-Cells and 65 for B-Cells is the threshold for positive. Single antibody beads (Thermo Fisher) were used for HLA antibody identification. UAgs are listed based on mean fluorescence intensity (MFI) of 1000 for Class I and 3000 for Class II. Results All the cases were evaluations for deceased-donor kidney transplantation. Case 1: A re-transplant candidate with 100% cPRA had an unexpected strong positive T-FCXM (MCD over 400) with no known Class I DSA. A serum tested at a 1/10 dilution showed two Class I DSAs, A2 and B57 with a combined peak MFI of 10,303. Case 2: A B-FCXM was reported as strong positive with a MCD of 378. The patient had strong autoantibody reacting with his B-Cells (MCD 270). Subsequent B-FCXMs were reported as uninterpretable because of a history of auto-antibody reacting with B-Cells with no known DSA. The patient was successfully transplanted. Case 3. A patient with a negative antibody history and no auto-antibody had an unexpected positive T-FCXM (MCD 192). The B-FCXM was Negative. A new HLA antibody profile was negative. A new auto-crossmatch was T-FCXM positive(MCD 73) and B-FCXM negative. Subsequent T-FCXMs were reported as uninterpretable because of a history of auto-antibody reacting with T-Cells with no known DSA. The patient was successfully transplanted. Conclusions 1. A prozone effect must be evaluated when listing UAgs. 2. Unexpected FCXM results should be investigated. 3. The clinical relevance of the FCXM result must be communicated to prevent a patient being removed from consideration, inappropriately.
Databáze: OpenAIRE
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