Comparative analysis of complement-dependent lymphocytotoxicity crossmatch and flow cytometry crossmatch results versus Luminex single-antigen bead-based donor-specific IgG class I antibody MFI values in live related renal transplant cases; a retrospective observation in 102 cases.

The aim of this study was to compare the results of solid phase assay and cell-based assay, and explore the near-accurate DSA-MFI-cutoff value detected on solid phase assay above which the cell-based assay would show a positive result. In this retrospective study, 102 prospective renal transplant recipients were tested for the presence of donor-specific antibodies (DSAs) by cell-based assay (T-cell-CDC-AHG-XM and T-cell-IgG-FC-XM) and solid phase assay (class-I-IgG-L-SAB) with their corresponding donor. Among the 40 patients in the group first (L-SAB-DSA-MFI<1000), one case was positive in IgG-T-cell-FC-XM while T-cell-CDC-AHG-XM was negative in all the cases. In the second group having L-SAB-DSA-MFI values between 1000 and 3000, 19 cases were positive and the remaining 11 cases were negative in IgG-T-cell-FC-XM. T-cell-CDC-AHG-XM showed a negative reaction in all 30 cases. In the third group having L-SAB-DSA-MFI values between 3000 and 5000, IgG-T-cell-FC-XM was positive in 18 cases while, two were negative. T-cell-CDC-AHG-XM demonstrated a negative result in 14 cases while reaming six cases demonstrated a positive result. In the fourth group having L-SAB-DSA-MFI values >5000, all 12 cases showed a positive result in both IgG-T-cell FC-XM and T-cell-CDC-AHG-XM. Our results indicated that the L-SAB-DSA-MFI values >2215 were significantly (P < .001) correlated with positive IgG-T-cell-FC-XM while L-SAB-DSA-MFI values >4689 were significantly (P < .001) correlated with positive CDC-XM.

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.

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.