2.Causes of Positive Pretransplant Crossmatches in the Absence of Donor-Specific Anti-Human Leukocyte Antigen Antibodies: A Single-Center Experience
Hyunhye KANG ; Jaeeun YOO ; Sang-Yoon LEE ; Eun-Jee OH
Annals of Laboratory Medicine 2021;41(4):429-435
Pretransplant crossmatch (XM) testing is widely used for detecting preformed donor-specific antibodies (DSAs) against human leukocyte antigen (HLA). However, in some cases, there is a positive XM result in the absence of HLA-DSAs, the cause of which was rarely identified. We reviewed the causes of sequential positive XM results at a single center and analyzed the presence of non-HLA antibodies in patients with an unexplained positive pretransplant XM result. Among 251 patients with T-cell/B-cell complement-dependent cytotoxicity (CDC) or flow cytometric crossmatch (FCXM) positivity, HLA-DSAs were confirmed in 88 (35.1%) by a single antigen bead (SAB) assay, 150 (59.8%) used rituximab (anti-CD20), and 13 (5.2%) had neither HLA-DSAs nor a desensitization history. Anti-angiotensin II type 1 receptor IgG and 33 non-HLA antibodies were tested in the 13 patients with an unexplained positive pretransplant XM result, and more than one non-HLA antibody were revealed in all these patients; 11 patients had non-HLA antibodies reported to be associated with graft rejection, and two patients experienced rejection episode after kidney transplantation. Our study suggests considering non-HLA antibodies testing when a CDC or FCXM test is positive without a definite cause. Assessing non-HLA antibodies might be useful for interpreting XM results and evaluating immunologic risk in transplant recipients.
4.Assessment of Long-Term Stability of External Quality Control Materials: Defibrinated Pooled Plasma for Examination of Hepatitis Viral Markers
Hyunhye KANG ; Dong Wook JEKARL ; Seung Hyo YOO ; Ae-Ran CHOI ; Eun-Jee OH
Journal of Laboratory Medicine and Quality Assurance 2024;46(1):66-71
Since 2016, the external quality assessment program of The Korean Association of External Quality Assessment Service for hepatitis serology has employed pooled serum specimens. Ten test items include hepatitis B virus surface antigen (HbsAg), hepatitis B virus surface antibody (anti-HBs), hepatitis B virus core antibody (anti-HBc) total, anti-HBc immunoglobulin M (IgM), hepatitis B virus envelope antigen (HBeAg), hepatitis B virus envelope antibody (anti-HBe), hepatitis C virus antibody (anti-HCV), hepatitis A virus antibody (anti-HAV) total, anti-HAV immunoglobulin G (IgG), and anti-HAV IgM. We aimed to evaluate the long-term stability of pooled serum specimens using fresh frozen plasma stored at different temperatures. In the first trial conducted in 2019, an additional 432 samples were prepared and tested for long-term stability at room temperature for 2 weeks, refrigerated for 1 month, and frozen (-20℃ and -80℃) for 6 months to 1 year. Furthermore, the stability of the samples was evaluated based on the number of repeated refrigeration and freezing cycles. The prepared pooled sera specimens for hepatitis serology were stable for up to 10 days at 2–8℃, 2–3 months at -20℃ and -80℃, and four freeze-thaw cycles, with the quantitative indices of all tests deviating within 10%. The results of this study are expected to contribute to the stable implementation and quality improvement of the hepatitis virus antigen-antibody test reliability survey project.