Low ionic antiglobulin tests.

Seven serologic procedures were studied to determine their respective value in compatibility and screening tests. All seven were significantly improved by the use of 4 volumes of serum, rather than 1, with 1 volume of red cell suspension, and a low-ionic antiglobin test (LIAGT) was distinctly superior to the other six procedures evaluated. In this test, during the incubation of serum and cells at 37 degrees for 20 minutes, ionic concentration was reduced 62 percent. However, after removal of all supernatant, the red cells were washed three times with an isotonic solution that provided 80 percent reduction in ionic concentration, and the washed cells were tested for their agglutinability with low-ionic (80% ionic reduction) anti-IgG antiglobin reagent. This modified LIAGT was usually more, and apparently never less, sensitive than a test described earlier and is expected to be associated with much less nonspecificity. The extreme sensitivity of LIAGT for many long-term frozen stored alloantiserums is a retained property of the modified test and has been associated with IgG aggregation during storage.