Abstract:
We have reviewed the literature to identify and characterize reports of warm-antibody type, autoimmune hemolytic anemia in which the standard direct antiglobulin reaction was negative but a confirmatory test indicated that the red cells were opsonized with antibody. Three principal reasons account for the absence of a positive direct antiglobulin test in these cases: a) IgG sensitization below the threshold of detection by the commercial antiglobulin reagent, b) low affinity IgG, removed by preparatory washes not conducted at 4°C or at low ionic strength, and c) red cell sensitization by IgA alone, or rarely (monomeric) IgM alone, but not accompanied by complement fixation, and thus not detectable by a commercial antiglobulin reagent that contains anti-IgG and anti-C3. In cases in which the phenotype is compatible with warm-antibody type, autoimmune hemolytic anemia and the direct antiglobulin test is negative, an alternative method to detect low levels of IgG sensitization, use of 4°C, low ionic strength washes to prepare the cells for the direct antiglobulin test reaction to permit retention and identification of low affinity IgG antibodies, and, if the latter are uninformative, testing for sensitization with an anti-IgA, and, if necessary, an anti-IgM reagent identifies cases of warm-antibody type, immune hemolysis not verified by a commercial reagent.
摘要:
我们回顾了文献,以鉴定和表征温抗体类型的报道,自身免疫性溶血性贫血,其中标准直接抗球蛋白反应为阴性,但确证试验表明红细胞经抗体调理。在这些情况下,没有阳性直接抗球蛋白测试的三个主要原因:a)IgG致敏低于商业抗球蛋白试剂的检测阈值,b)低亲和力IgG,通过不在4°C或低离子强度下进行的预备洗涤去除,和c)单独通过IgA的红细胞致敏,或很少单独(单体)IgM,但不伴有补体固定,因此不能被含有抗IgG和抗C3的商业抗球蛋白试剂检测到。在表型与温抗体类型相容的情况下,自身免疫性溶血性贫血和直接抗球蛋白试验阴性,一种检测低水平IgG致敏的替代方法,使用4°C,低离子强度洗涤,以制备细胞的直接抗球蛋白测试反应,以允许保留和鉴定低亲和力IgG抗体,and,如果后者没有信息,用抗IgA进行致敏测试,and,如有必要,抗IgM试剂可识别温暖抗体类型的病例,未通过商业试剂验证的免疫溶血。