Ahaded A, Brossard Y, Debbia M, Lambin P
Immunology Transfusion Service Unit, National Institute of Blood Transfusion, Paris, France.
Transfusion. 2000 Oct;40(10):1239-45. doi: 10.1046/j.1537-2995.2000.40101239.x.
Severe cases of HDN occur after the immunization of the mother with K (KEL1) antigen. To date, the only means of evaluating the concentration of anti-K in maternal serum is by titration with an indirect antiglobulin test (IAT). A more accurate estimation of the serum anti-K concentration is needed.
An ELISA technique was developed for the determination of the absolute concentration of anti-K IgG and IgG subclasses in the sera of alloimmunized patients. In this technique, after absorption of anti-K on K-positive RBCs and subsequent elution at acid pH, the concentration of anti-K in the eluate was measured with a sensitive and reproducible ELISA. This method was validated with monoclonal and polyclonal anti-K. It was then used to assay the sera of eight pregnant women with anti-K immunization, associated with early fetal anemia (Hct, 7-17%) detected between the 20th and the 31st week of pregnancy. In addition, in most of these cases, the anemia was associated with fetal hydrops.
The anti-K IgG concentration measured by ELISA in the sera of the eight women varied from 1.0 to 4.1 microg per mL (mean, 2.2 microg/mL). Therefore, severe and early forms of fetal anemia can be observed with a relatively low concentration of anti-K (as compared to the concentration of anti-D in similar cases of fetal anemia due to anti-D). The mean proportion of each IgG subclass of anti-K in these sera was IgG1, 95.9 percent; IgG2, 2.4 percent; IgG3, 1.3 percent; and IgG4, 0.4 percent.
A simple method for quantitative estimation of anti-K in human serum has been developed. Low concentrations of anti-K can cause fetal anemia relatively early in pregnancy. This method should lead to a better identification of pregnant women whose fetuses are at risk for severe fetal anemia due to anti-K.
母亲接种K（KEL1）抗原后会发生严重的新生儿溶血病（HDN）。迄今为止，评估母血清中抗-K浓度的唯一方法是通过间接抗球蛋白试验（IAT）进行滴定。需要更准确地估计血清抗-K浓度。
开发了一种酶联免疫吸附测定（ELISA）技术，用于测定同种免疫患者血清中抗-K IgG及其亚类的绝对浓度。在该技术中，抗-K吸附在K阳性红细胞上，随后在酸性pH下洗脱，用灵敏且可重复的ELISA测定洗脱液中抗-K的浓度。该方法用单克隆和多克隆抗-K进行了验证。然后用于检测8名抗-K免疫的孕妇血清，这些孕妇在妊娠第20至31周期间出现早期胎儿贫血（血细胞比容，7 - 17%）。此外，在大多数这些病例中，贫血与胎儿水肿有关。
通过ELISA测定的8名女性血清中抗-K IgG浓度在每毫升1.0至4.1微克之间（平均，2.2微克/毫升）。因此，与因抗-D导致胎儿贫血的类似病例中的抗-D浓度相比，相对较低浓度的抗-K就能观察到严重的早期胎儿贫血形式。这些血清中抗-K各IgG亚类的平均比例为：IgG1，95.9%；IgG2，2.4%；IgG3，1.3%；IgG4，0.4%。
已开发出一种简单的定量估算人血清中抗-K的方法。低浓度的抗-K可在妊娠早期相对较早地导致胎儿贫血。该方法应能更好地识别其胎儿因抗-K有严重胎儿贫血风险的孕妇。
