Campbell K, Rishi K, Howkins G, Gilby D, Mushens R, Ghevaert C, Metcalfe P, Ouwehand W H, Lucas G
National Health Service Blood and Transplant, Cambridge Centre, Long Road, Cambridge CB2 2PT, UK.
Vox Sang. 2007 Nov;93(4):289-97. doi: 10.1111/j.1423-0410.2007.00989.x.
The monoclonal antibody-specific immobilization of platelet antigens (MAIPA) assay is the cornerstone technique for the detection and identification of human platelet antigen (HPA) antibodies. However, the original technique described by Kiefel and colleagues requires approximately 8 h adding to diagnostic delay. Moreover, proficiency exercises indicate that there are substantial variations in the MAIPA protocol, and that these may account for interlaboratory differences in sensitivity and specificity.
A review of current MAIPA assay protocols from six laboratories together with performance in quality-assessment schemes identified several key variables potentially affecting the assay results. An optimized protocol was derived and assay time reduced to 5 h. The modified rapid MAIPA (MR-MAIPA) assay was evaluated using 61 samples with a range of HPA antibodies typically encountered in cases of fetomaternal alloimmune thrombocytopenia (n = 22), post-transfusion purpura (n = 8), platelet refractoriness (n = 7) and other platelet immune conditions (n = 24). The sensitivity of the assay was assessed using three international standards and the recombinant HPA-1a antibody CamTran007. The results obtained were compared with the original findings obtained with the local MAIPA assays. In addition, four different glycoprotein IIb/IIIa capture monoclonal antibodies were evaluated for their effect on assay sensitivity.
Complete concordance was found between the original MAIPA results and those obtained with the new assay when testing a selected panel of clinical samples. The modified assay had nanogram level sensitivity for the detection of HPA-1a antibodies and titration of HPA-1a and HPA-5b antibody sensitivity standards yielded end-points equal to or greater than the mean recorded in international workshops.
The MR-MAIPA assay offers improved turnaround for the detection of HPA antibodies without loss of sensitivity.
血小板抗原单克隆抗体特异性固定检测法（MAIPA）是检测和鉴定人类血小板抗原（HPA）抗体的核心技术。然而，基费尔及其同事最初描述的技术需要约8小时，这会增加诊断延迟。此外，能力验证表明MAIPA方案存在很大差异，这可能是实验室间敏感性和特异性差异的原因。
回顾了六个实验室当前的MAIPA检测方案以及质量评估计划中的表现，确定了几个可能影响检测结果的关键变量。由此得出了优化方案，并将检测时间缩短至5小时。使用61份样本对改良的快速MAIPA（MR-MAIPA）检测法进行了评估，这些样本涵盖了胎儿母体同种免疫性血小板减少症（n = 22）、输血后紫癜（n = 8）、血小板输注无效（n = 7）和其他血小板免疫疾病（n = 24）中常见的一系列HPA抗体。使用三种国际标准品和重组HPA-1a抗体CamTran007评估了该检测法的敏感性。将获得的结果与当地MAIPA检测法的原始结果进行了比较。此外，评估了四种不同的糖蛋白IIb/IIIa捕获单克隆抗体对检测敏感性的影响。
在检测一组选定的临床样本时，原始MAIPA结果与新检测法获得的结果完全一致。改良后的检测法对HPA-1a抗体的检测具有纳克级敏感性，HPA-1a和HPA-5b抗体敏感性标准品的滴定终点等于或高于国际研讨会记录的平均值。
MR-MAIPA检测法在不损失敏感性的情况下，提高了HPA抗体检测的周转效率。
