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BACKGROUND: Polyethylene glycol (PEG) has been shown to potentiate antigen-antibody reactions. STUDY DESIGN AND METHODS: To investigate the utility of PEG in pretransfusion testing, a blinded comparison study of PEG and a low-ionic-strength additive solution (LISS) was conducted. A total of 500 patient samples were tested in parallel with reagent antibody-detection cells using blind-coded PEG and LISS potentiators. RESULTS: In 34 (34%) of 100 samples with known antibodies in the Rh, Kell, Duffy, Kidd, and MNS systems, PEG antiglobulin reactions were stronger (total score, 382) than LISS antiglobulin reactions (total score, 216), and in 66 cases (66%), they were equal to those of LISS. Of 400 samples without detectable antibodies, 384 were negative with PEG and LISS, and 16 were positive in PEG tests and negative in LISS. Seven of the 16 were clinically important antibodies (D, 1; E, 3; Fya, 1; Jka; 1; Jkb, 1), and four were clinically benign antibodies (Le(a), 2; McCc, 1; Sda, 1). Five of the 16 demonstrated inconclusive PEG reactions, for a false-positive rate of 5 in 400 (1.3%). Of the 500 samples, none was negative in PEG tests and positive in LISS (0% false-negative rate). CONCLUSION: Although PEG demonstrates a relatively high false-positive rate, PEG is more sensitive than LISS in detecting clinically significant antibodies.

Low-ionic-strength saline (LISS) techniques permit a safe and substantial reduction in incubation time and have therefore become the method of choice for antibody detection and compatibility testing in many transfusion laboratories. Consequently, the supply of reagent red cells (RBCs) in a low-ionic-strength preservative solution would remove the daily need for laboratories to wash and resuspend cells in LISS before use. However, the storage of fresh RBCs at low ionic strength in the presence of aminoglycoside antibiotics can cause a rapid loss of certain antigens, possibly as a result of the release of proteolytic enzymes from contaminating white cells. This article describes a low-ionic-strength solution that achieves preservation of antigens on liquid nitrogen-frozen-thawed RBCs for 21 days' storage at 4 degrees C.

Manual hexadimethrine bromide (Polybrene) tests (Polybrene in low-ionic medium) were used in parallel with manual low-ionic-strength solution (LISS) procedures for the routine testing of patient samples referred to a general hospital blood bank. Of 5646 consecutive sera tested, 5167 (91.5%) did not react with either technique; 320 sera (5.7%) reacted in both methods. The Polybrene technique detected 63 antibodies which did not react in the LISS methods. One hundred sera did not react in the Polybrene test, but did react in the LISS methods. Sera showing discrepant results between the two methods were further tested in a reference laboratory. Polybrene tests appeared to be better in avoiding reactions due to clinically nonsignificant antibodies. The LISS methods, however, appeared to be more sensitive in detecting antibodies of potential clinical significance.

The sensitivities of manual low-ionic hexadimethrine bromide (Polybrene, LIP) and low-ionic Polybrene indirect antiglobulin tests (LIPAT) were compared with those of a manual low-ionic-strength indirect antiglobulin test (LISS) by using a commercial Polybrene kit. One hundred antibodies were coded, titrated, and tested in parallel. LIP did not detect 36 antibodies: 31 anti-K, two anti-E, two anti-Fya, and one anti-Jka. LIPAT did not detect seven anti-K, two anti-E, and two anti-Jka. The combination of LIP and LIPAT did not detect two anti- E that were reactive only in a two-stage enzyme test and seven anti-K that had titers of 2 or lower by LISS. LISS detected all antibodies except for the two enzyme-reactive anti-E. There were no significant differences in the titers of 63 percent of the antibodies studied. For 54 percent of the antibodies in the Kell system, LISS produced significantly higher titers; for 25 percent of antibodies in the Rh system, LIP did so. The poor sensitivity of the Polybrene kit for anti- K makes it unsuitable as a primary method for antibody screening.

The low ionic strength solution (LISS) of Low and Messeter was compared with both the automated low ionic strength Polybrene and the manual IDAT techniques. A five minute incubation with the LISS was sufficient to detect all significant antibodies. By extending the incubation period to 15 minutes it was possible to increase the sensitivity of the reaction (as measured by titer) beyond that of either of the other methods. This LISS procedure has enabled us to greatly extend the applications of a “standby procedure” for elective surgery. In this procedure routine crossmatching is not done. Rather, the blood is placed on standby and if required, transfusion is provided by using the LISS. In one general hospital this resulted in the reduction by 1,600 units of unnecessary crossmatches and an increase of 10 per cent in the total blood utilization rate over a nine-month period.

Three different techniques of antibody screening of donor bloods were sequentially evaluated. Group I (16300 donors) was a standard saline-albumin-AHG technique utilizing polyvalent serum, including incubation at room temperature. In Group II (26,243 donors), incubations (including room temperature) were performed in I. ISS, and monovalent anti-IgG serum was used. For Group III (15,840 donors), the room temperature incubation was not used for the LISS-IgG method of Group II. The three methods were comparable in terms of detection of clinically significant antibodies, while in Group III the detection of clinically nonsignificant antibodies was eliminated. Cost analysis indicates that for a donor center processing approximately 50,000 units per year and willing to prepare its own LISS solutions, conversion to LISS-IgG could produce a savings of between $5,000 and $8,000 per year. LISS-IgG is thus a sensitive and economical technique highly recommended for the donor center committed to manual donor antibody screening.

Human and simian red blood cells were tested for 125I anti-D binding at equilibrium and for their ability to adsorb 125I anti-D. On the basis of the equilibrium quantity of red blood cell-bound anti-D at different ionic strengths, the rate of binding of anti-D, and adsorption studies, evidence has been obtained that D-antigenic specificities occur on the erythrocytes of orangutans (Pongo pygmaeus), chimpanzees (Pan troglocytes) and gorillas (Gorilla gorilla). Gorillas, like chimpanzees, appear to be polymorphic with respect to the presence of D-components on their erythrocytes. Individual animals have been found whose red blood cells take up very little anti-D and are similar to human D-negative cells. The quantity of anti-D bound at equilibrium, as a fraction of that bound to human D-positive red blood cells was: for gorillas 0.6 to 4.0; for chimpanzees 0.08 to 0.51; for orangutans 0.06 to 0.09, and for human Du red blood cells 0.04. At low ionic strength there was almost a twofold increase in anti-D binding. At low ionic strength, the adsorbing capacities of these erythrocytes, as compared to a human D-positive cell, were: orangutans 10 to 20 per cent; chimpanzees about 50 per cent; human Du 86 per cent; and gorillas 97 per cent. Evidence is presented to indicate that the discrepancy between adsorbing capacity and the binding of anti-D at equilibrium, for Du and simian erythrocytes, is due to absence of some of the D-antigenic components found on human D-positive red blood cells.

Antibody detection studies were undertaken in order to compare a low ionic strength (LIS) medium with a conventional albumin-fortified isotonic medium. Tests were performed in parallel with both media at room temperature and at 37 C. A 30mM NaCl solution was used as the LIS medium and in this study this enhanced antibody reactions without causing nonspecific reactions. The LIS medium detected all of more than 50 Rh and more than 75 non-Rh antibodies after 15 minutes of incubation. Often 30 to 60 minutes of incubation were required to detect these antibodies by the routine method. Several antibodies that were detected with the LIS medium after 15 minutes of incubation were either undetected or had given a nonspecific pattern of activity after 60 minutes incubation in the routine medium. When an antibody was present, the LIS medium invariably gave stronger, more clear-cut results. It is concluded that the LIS medium is generally more sensitive than a conventional medium in detecting antibodies since such a medium will detect clinically significant antibodies after only 15 minutes incubation as well as detect antibodies missed by a conventional medium. An antibody detection system utilizing this medium has obvious applicability to a hospital transfusion service.