A new potentiator of red blood cell antigen-antibody reactions.

A new technic using polyethylene glycol (PEG) was developed to detect and enhance weak red blood cell/antibody reactions. Twenty percent PEG of 4,000 molecular weight was found to be optimal. Weakly reactive antibodies (n = 25) were tested by PEG, Polybrene, and low ionic strength saline (LISS); 64% were strongest in PEG, 28% reacted equally in PEG as in Polybrene or LISS, 8% reacted weaker in PEG than in Polybrene or LISS. Stronger antibodies (n = 11) were titrated and compared in the three technics; in 10 of 11 titrations, PEG was better or equal to Polybrene and LISS. The false positive rate with the use of PEG and anti-IgG was 1.5% with the use of random sera. Sera from patients (n = 24) with hemolytic transfusion reactions and no detectable antibody by routine technics were tested; two sera had specific antibodies by the PEG technic. This new technic should be a valuable aid in the detection and identification of weak antibodies.