Phycoerythrin-conjugated Goat Anti-Human IgG is used with the Luminex assays to detect the presence of human IgG. The PE-conjugated antibodies to human IgG bind to either cell surface antigens or purified antigens immobilized onto microspheres. The fluorescent emission detected by a flow analyzer indicates the presence of human IgG.
With the recent changed in dilution of PE conjugate, many laboratories had reported lower PC values in their samples. The overall MFIs of each sample were lower, resulting in lesser antibodies above the cut-off.
In this study, we have tested 10 known samples with vendor’s recommended dilution (reconstituted with 2ml water) PE, 1.5ml and 1ml PE. Our laboratory use MFI value greater than 1000 as cut off for positive reaction. The Class I and II HLA antibodies were in concordance with the known results except for Class I antibodies in Sample 5. Anti- HLA A11, A24 and A36 were missed with 2ml PE whereas Anti-HLA A11 and A36 were missed with 1ml PE.
Although all antibodies were in concordance with known results for tests performed with 1.5ml PE, more samples need to be included as the sample size was too small.