Ｐｒｅｗａｒｍ ｔｅｃｈｎｉｑｕｅはＲｈ系抗体の検出率を低下させる

Abstract

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 5min and the extent of this decrease was enhanced at 120min. 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 antibodies-induced RBC agglutination but also warm-reactive antibodies-induced RBC agglutination.