Significance of Luminex-based single antigen class II bead assay and its mean fluorescence intensity in renal transplant cases; a retrospective observation in 97 cases

• Published in: Journal of immunoassay & immunochemistry Vol. 41; no. 3; pp. 322 - 336
• Main Authors: Pande, Amit, Pandey, Prashant, Kumar Devra, Amit, Kumar Sinha, Vijay, Prasad Bhatt, Anil
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 03.05.2020; Marcel Dekker, Inc
• Subjects: Adult; Antibodies; Antibodies - immunology; Antigens; Assaying; CDC-AHG-XM; Cytotoxicity; Diagnostic systems; donor-specific anti-HLA antibodies; DSA; Female; Flow cytometry; Fluorescence; Globulins; Histocompatibility antigen HLA; Histocompatibility Antigens Class II - analysis; Histocompatibility Antigens Class II - immunology; Histocompatibility Testing; HLA; Humans; Immunoglobulin G; Kidney Transplantation; Leukocytes; Lymphocytes B; Male; mean fluorescence intensity; Microscopy, Fluorescence; Middle Aged; Retrospective Studies; Sensitivity; Toxicity; mean fluorescence intensity; CDC-AHG-XM; flow cytometry; DSA; donor-specific anti-HLA antibodies; HLA
• ISSN: 1532-1819; 1532-4230
• DOI: 10.1080/15321819.2020.1736095

The objective of this study was to determine the mean fluorescence intensity (MFI) values of class II Luminex single antigen bead (L-SAB) assay and compare these MFI values with cell-based complement-dependent cytotoxicity crossmatch with anti-human globulin (CDC-AHG-XM) and IgG-B-cell flow cytometry crossmatch (FC-XM) results and explore the near-accurate MFI-cutoff values of positive cell-based crossmatch results. This retrospective study was an analysis in 97 renal transplant recipients, who were tested for the presence of DSA by CDC-AHG-XM and IgG-B-cell-FC-XM methods with their corresponding donor as well as for anti-human leukocyte antigen (HLA) antibody detection using a sensitive L-SAB assay. In the group having DSA MFI values <1000, none of the patients showed positivity for FC-XM and CDC-AHG-XM; in the group having MFI values between 1000 and 3000, 35.48% showed positivity for FC-XM but none by the CDC-AHG-XM method. However, in the group having MFI values >3000, 83.33% of cases were positive for FC-XM. Further, in those groups with MFI values between 3000 and 6000, 38.09% were positive for CDC-AHG-XM, while 86.66% showed positivity in the group with MFI >6000. Our results indicated that Luminex-DSA MFI value >1995 (P < .0001) significantly correlated with IgG-B-cell-FC-XM positivity while Luminex-DSA MFI value of >4247 (P < .0006) was significantly correlated with positive CDC-AHG-XM. MFI cutoff of 1995 exhibited a diagnostic sensitivity of 97.56% and specificity of 89.29% for predicting positive IgG B-cell FC-XM and MFI cutoff of 4247 exhibited a diagnostic sensitivity of 90.48% and specificity of 97.37% for predicting positive CDC-AHG-XM. However, a cutoff MFI of >5000 and >7000 for SAB assay had a sensitivity and specificity of 100% in detecting a positive IgG B-cell FC-XM and CDC-AHG-XM, respectively.