A new bead-based human platelet antigen antibodies detection assay versus the monoclonal antibody immobilization of platelet antigens assay
- The PAKLx tests were provided by Gen-Probe Diagnostics, Inc. and PAKLx materials were provided by Lifecodes products, HOLOGIC/Gen-Probe.
The performance of a newly developed Luminex bead-based platelet (PLT) antibody detection method (PAKLx) was compared with the monoclonal antibody immobilization of PLT antigens (MAIPA) assay and the LifeScreen Deluxe Luminex bead-based HLA Class I antibody detection method (LMX).
Study Design and Methods
Six sera containing anti-human PLT antigen (HPA)-1a (n = 2), HPA-1b, HPA-2b, HPA-3a, or HPA-5b were tested in titration. A total of 194 sera, including HPA-1a, -1b, -2a, -2b, -3a, -5a, and -5b antibodies with or without HLA antibodies (n = 63); glycoprotein (GP) IV antibodies (n = 1); PLT autoantibodies (n = 3); HLA antibodies (n = 45); and samples with no PLT-reactive antibodies (n = 82), were tested in both assays.
Comparable levels of sensitivity were obtained for the MAIPA and PAKLx. The PAKLx showed four (6%) false-negative results in 67 sera with HPA or GP-reactive antibodies: anti-HPA-3a (n = 1) or anti-HPA-5b (n = 3). The PAKLx showed in 10 of the total 194 samples (5%) the presence of antibodies not detected by the MAIPA. This concerned broadly GP-reactive antibodies (n = 7), anti-GPIIb/IIIa combined with anti-HPA-3a (n = 1), anti-HPA-1a (borderline, n = 1), and anti-GPIV (n = 1). Testing 175 sera for anti-HLA Class I antibodies in the PAKLx and LMX showed four discrepant results: PAKLx negative and LMX positive, n = 3 and n = 1, respectively.
For the vast majority of the specimens tested (93%) the results of the PAKLx were in concordance with the MAIPA. The PAKLx is a fast, easy to perform, and sensitive PLT antibody screening method.