Improved detection of weak, clinically significant antibodies by supplementation of polyethylene glycol with a low-ionic solution.
A comparative study of 164 serum samples was carried out to determine the specificity and sensitivity of the indirect antiglobulin test (IAGT) in three different formulations: physiologic saline, low-ionic solution (RAM), and RAM supplemented with polyethylene glycol (PEG). Serum samples containing mostly weak antibodies (anti-D, -C, -E, -c, -Jka, -Fya, -K, -S, -Lea, -Lua, -M, -Cob, -P1, -I, and -Kna) were used in a 10-minute IAGT in which PEG-IAGTs were compared with saline- IAGTs and RAM-IAGTs. With the exception of anti-P1, anti-I, and an anti-Lea, PEG-IAGTs detected all the antibodies tested compared with 72.3% and 77.4% for saline-IAGTs and RAM-IAGTs, respectively. The end-point titers of at least 82% of antibodies detected by PEG-IAGTs were 1-3 dilutions higher than those by saline- and RAM-IAGTs. When specificity of PEG-IAGTs was tested using 268 randomly selected, fresh (< 1 day old) blood samples, PEG-IAGT detected 11 out of 268 samples as positive compared with 7 out of 268 by both saline-IAGTs and RAM-IAGTs. The four antibodies that were not detected were identified as anti-D, anti-E, anti-Bga, and an autoantibody known previously to be only reactive with papain-pretreated red cells. No nonspecific reactions were detected by PEG-IAGTs and no hemolysis was evident in any of the IAGTs. PEG-IAGTs were more sensitive than saline- and RAM-IAGTs. PEG-IAGTs detected all weak, clinically significant antibodies as well as four antibodies that were otherwise undetected by saline-IAGT or RAM-IAGT. The overall sensitivity of the PEGIAGT was 96.3% compared with 84.1% and 73.2% for the RAM- and saline-IAGT, respectively.
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Biosciences Division, CSL Limited, 45 Poplar Road, Parkville, Victoria, Australia.
Liew
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Bradley
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