Prewarm technique はRh系抗体の検出率を低下させる

Prewarm technique(PW), a method of warming reagents and samples before reaction, is used to prevent the effect of cold-reactive antibodies on the detection of warm-reactive antibodies. However, a recent report indicates the possibility that PW may attenuate the agglutination of red blood cells (RBC)induced by warm-reactive antibodies. In this study, we determined the effect of PW on detection efficiency for Rh system antibodies. We used 38 samples with Rh system antibodies(29 samples with anti-E antibody, 6 with anti-D antibody, 2 with anti-c antibody and 1 with anti-e antibody)which showed a positive reaction on 3 kinds of indirect antiglobulin tests(IAT)including 37°C saline IAT, low ionic strength saline(LISS)-IAT and the Polyethylene glycol(PEG)-IAT or bromelin method. Reduction of antibody titers induced by the prewarm technique was observed in 46.7% samples and 36.1% of samples tested by 37°C saline IAT and PEG-IAT, respectively. This reduction was observed more frequently in samples tested by LISS-IAT and the bromelin method(60.7% in LISS-IAT and 62.9% in the bromelin method). In samples with lower antibody titers(less than 2-fold), more than 30% of samples showed a negative reaction in LISS-IAT and the bromelin method. We then examined the effect a warming period on the Rh system antibodies-agglutination score. A decrease in agglutination score was observed on warming for 5 min and the extent of this decrease was enhanced at 120 min. In addition, we warmed the RBC suspension and plasma separately, and examined their effect on agglutination score. Since a decrease in agglutination score was observed only when the RBC suspension was warmed, warming of RBC may cause a decrease in warm-reactive antibodies reactivity. These results indicate that PW may attenuate not only cold-reactive antibodiesinduced RBC agglutination but also warm-reactive antibodies-induced RBC agglutination.