Antibody identification using both automated solid-phase red cell adherence assay and a tube polyethylene glycol antiglobulin method

BACKGROUND: Because antibody identification is labor-intensive, facilities with high volume and/or marginal technical support could benefit from partial automation. STUDY DESIGN AND METHODS: After a validation study of automated solid-phase red cell (RBC) adherence assay (SPRCA; Galileo, Immucor) compared to tube polyethylene glycol antiglobulin antibody identification method (t-PEG), we evaluated Galileo followed by select RBC panels by t-PEG. Of 298 consecutive samples in which antibody identifications were performed in a 2-month period, 160 samples were examined by both Galileo and t-PEG. RESULTS: There were concordant results between Galileo and t-PEG in 120 of 160 (75%) samples including cases with identical alloantibody identification (n = 99), panagglutinin (n = 9), and negative results (n = 12). Of the samples in which alloantibodies were identified, 99 of 108 (91.7%) were identical. In 9 samples with discrepant antibody identifications, 2 samples showed alloantibody specificity by Galileo (possible anti-K and anti-Jk^b) but were negative by t-PEG. These antibodies were identifiable by t-PEG in subsequent samples. One sample showed anti-E by Galileo, while t-PEG revealed anti-Fy ^a and -E. Five samples showed alloantibody specificity by t-PEG and nonspecific reactivity or panagglutinin by Galileo. These included samples with anti-C (n = 2), anti-E (n = 2), and anti-Fy^a (n = 1). One sample showed anti-E by t-PEG but was negative by Galileo. Galileo found a panagglutinin in 23 samples and nonspecific reactivity in 22 samples, whereas t-PEG found a panagglutinin in 12 samples but no nonspecific reactivity. CONCLUSIONS: Automated Galileo solid-phase red cell adherence assay can be a useful adjunct for antibody identification, although it detects more nonspecific reactivity than does t-PEG.