Representative sera were selected for the evaluation of EDTA treatment: Sera previously characterized to be Negative for anti-HLA; Sera previously characterized to be Positive for anti-HLA; Sera previously characterized to be Negative for anti-HLA by Luminex and positive by CDC, Masked sera. Two aliquots of each serum, untreated & treated with EDTA (5 ¦Ìl EDTA/95 ¦Ìl serum), were tested for HLA Abs using One Lambda Class I/II Single Antigen Bead assay. The trimmed mean MFI values were compared between untreated & EDTA treated samples.
The major findings from our study were:
EDTA treatment of known Negative sera did not convert negative to positive results
EDTA treatment of known Positive sera did not convert positive to negative results; however some of the positive sera gave higher MFIs after treatment
EDTA treatment of sera previously found to be Luminex negative and CDC positive resulted in a substantive increase in the MFIs in the sera with low MFIs.
Our encouraging results advance the idea that EDTA treatment of serum may help resolve the paradox of low MFI with the donor HLA by the Luminex platform and positive CDC and FCXM results.