LAUSR

Aim In this study we correlated flow and CDC- crossmatch outcomes with results of Luminex-single antigen bead (SAB). Methods Between 2010–2016 HLA-antibody Sera were tested by screening and SAB class I & II (One lambda) according to manufacturer recommendation. MFI of ⩾1000 were considered positive. These sera were used to perform the following: 1. 80 crossmatches using isolated PB or spleen lymphocytes from healthy deceased or living donors respectively by CDC–crossmatch. Correlation was performed on sera with single antibody or multiple classes I and II antibodies. Titer of CDC was given as the inverse of the highest dilution yielding positive XM. 2.108 FCXM cross using isolated PB donor lymphocytes expressing one HLA- antigen (class I or II) and 78 crossmatches using cells expressing multiple antigens detected by the sera. Analysis performed on FACSCanto II & mean channel shift (MCS) was calculated. The cut off for T &B are 64, 100 respectively. T- Positive, B- negative results in the absence of HLA- antibody were excluded from the study. Results Our results indicate good correlation of FCXM and CDC-XM with LUMINEX -SAB assay. SAB assay has good correlation with T-FCXM (r2 = 0.7) but not with B-FCXM. Fig. 1 A cutoff MFI of 3000 for SAB assay (as single or sum of multiple weak antibodies) had a sensitivity & specificity of 100% in detecting a positive FCXM. The few number of sera with single anti HLA-Cw and DP antibodies did not give positive reaction up to 5000 and 10,000 MFI respectively but were not included in the study. Single anti HLA-A, B, DRB1of ⩾10,000 MFI was associated with positive CDC-XM in most cases and multiple low levels antibody that yield this 10,000 would also give positive reaction. We noticed presence of A2 specificity among multiple anti class I or class II antibodies increased the chance of positive reaction even when sum of MFI is ⩽10000. Conclusions SAB correlates significantly with outcome of both cytotoxic and T-FCXM. Based on the threshold established it is possible to predict correctly results of crossmatch. Download : Download high-res image (164KB) Download : Download full-size image