The gel test: use in the identification of unexpected antibodies to blood group antigens

The IgG GEL test was compared with the LISS tube test (Löw and Messeter's low-ionic-strength saline) for antibody identification. The suitability of red blood cells (RBCs) pretreated with ficin, dithiothreitol (DTT), or chloroquine diphosphate (CDP) also was assessed for use in the GEL test. In addition, time-in-motion studies were performed comparing GEL (12 panels per batch) with polyethylene glycol (PEG) tube tests (3 panels per batch). In 57 antibody identification studies, there were 63 GEL+ LISS+, 2 GEL+ LISS-, and 6 GEL-LISS+ antibodies. Among the GEL+ LISS+ antibodies were 19 that yielded stronger reactions in GEL than in LISS; by virtue of their specificity, 14 of these are considered potentially significant: D, 5 E, 2 e, 2 Jka, 2 S, K, and Fya. There were 38 antibodies that yielded equivalent results by both methods, including 31 that are considered potentially significant. Of six antibodies with significantly greater reactivity in LISS, there were three anti-Rh and three that are considered harmless with respect to transfusion management. The two GEL+ LISS- antibodies (anti-Jkb) were potentially significant. GEL- LISS+ reactions involved only harmless antibodies. Of the 50 antibodies of potential significance, GEL yielded equivalent or superior results in 47 (94%) instances. Additionally, GEL failed to detect 6 of 21 harmless antibodies. Expected results were obtained with normal serum or plasma and antibodies of known specificity in tests with RBCs treated with ficin, DTT, or CDP. Hands-on-time required for each GEL panel was 2 to 21/2 minutes compared with 12 minutes for PEG. These data document the suitability of GEL for use in antibody identification studies.