Chaudhary Rajendra, Das Sudipta S, Gupta Ritu, Khetan Dheeraj
Department of Transfusion Medicine, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
Hematology. 2006 Aug;11(4):295-300. doi: 10.1080/10245330600915958.
Coombs negative autoimmune hemolytic anemia (AIHA) is characterized by laboratory evidence of in vivo hemolysis along with a negative direct antiglobulin test (DAT) performed by conventional tube technique (CTT) in clinically suspected AIHA patients. The sensitive gel test (GT) and flow cytometry (FC) can effectively diagnose such patients where CTT does not detect low level of red cell autoantibodies. We investigated the use of FC in the serological evaluation of CTT DAT negative AIHA and its comparison with GT DAT. Of the 50 patients with suspected AIHA, CTT DAT was negative in 5 patients (Coombs negative AIHA). GT DAT could detect red cell autoantibodies in 4 of these 5 patients. Monospecific GT DAT showed IgG and/or C3d as the responsible autoantibody. FC was considered as reactive when MFI was >3.6 (mean of 20 healthy negative volunteers +2SD). FC was reactive in all five Coombs negative AIHA patients. The mean MFI in five known CTT DAT positive samples taken for comparison was significantly higher compared to 5 DAT negative AIHA (18.3 +/- 7.78 vs. 7.88 +/- 1.35, p < 0.05). There was poor correlation between strength of GT DAT and MFI by FC. We conclude that FC is more sensitive test than the CTT and helps in the serological diagnosis of Coombs negative AIHA. However, in resource poor settings, GT DAT can be a good alternative to FC.
库姆斯阴性自身免疫性溶血性贫血（AIHA）的特征是，在临床疑似AIHA患者中，通过传统试管技术（CTT）进行的直接抗球蛋白试验（DAT）呈阴性，但存在体内溶血的实验室证据。灵敏的凝胶试验（GT）和流式细胞术（FC）能够有效诊断CTT无法检测到低水平红细胞自身抗体的此类患者。我们研究了FC在CTT DAT阴性AIHA血清学评估中的应用及其与GT DAT的比较。在50例疑似AIHA患者中，5例患者的CTT DAT呈阴性（库姆斯阴性AIHA）。GT DAT在这5例患者中的4例检测到了红细胞自身抗体。单特异性GT DAT显示IgG和/或C3d为相关自身抗体。当平均荧光强度（MFI）>3.6（20名健康阴性志愿者的平均值+2SD）时，FC被认为呈阳性反应。在所有5例库姆斯阴性AIHA患者中，FC均呈阳性反应。与5例DAT阴性AIHA患者相比，用于比较的5例已知CTT DAT阳性样本的平均MFI显著更高（18.3±7.78 vs. 7.88±1.35，p<0.05）。GT DAT强度与FC的MFI之间相关性较差。我们得出结论，FC比CTT更敏感，有助于库姆斯阴性AIHA的血清学诊断。然而，在资源匮乏的地区，GT DAT可以是FC的良好替代方法。
