ABSTRACT
EDTA/glycine-acid (EGA) has been reported to remove IgG-bound antibodies from red blood cells (RBCs) and to denature Kell system and Era antigens. EGA-treated RBCs were tested in parallel with chloroquine diphosphate (CDP)-treated RBCs to evaluate whether EGA would remove Bg antigens from RBCs as efficiently as CDP. Fifty-seven serum/plasma samples containing known Bg antibodies were tested with untreated Bg+ RBCs, EGA-treated Bg+ RBCs, and CDP-treated Bg+ RBCs by an indirect antiglobulin test (IAT), using a low-ionic-strength additive solution and murine monoclonal polyspecific antiglobulin reagent. Of 57 samples, 40 (22 anti-Bga, 17 anti-Bgb, and 1 Bg-related) were nonreactive by IAT with EGA-treated RBCs and CDP-treated RBCs, 14 (7 anti-Bga, 4 anti-Bgb, and 3 Bg-related) were nonreactive by IAT only with EGA-treated RBCs, none were nonreactive in IAT with only CDP-treated RBCs, and 3 (anti-Bga) were still reactive by IAT with EGA-treated RBCs and CDP-treated RBCs. Therefore, EGA strips Bg antigens from RBCs. Our results indicate EGA treatment is more efficient and requires less time (1-2 minutes) to perform than the CDP procedure (30-120 minutes) for removal of Bg antigens from RBCs.
ABSTRACT
Proteins G and A coated on agarose have been extensively used in affinity chromatography. Protein G will bind to all four subclasses of human IgG and protein A to the subclasses IgG1, IgG2, and IgG4. This IgG binding ability of protein G and protein A has been used in a red cell affinity column technology developed for the detection and identification of IgG red cell antibodies. When serum or plasma is incubated in a microcolumn with red blood cells (RBCs) that express the appropriate antigens, the antibodies become attached to the RBC surface. When the microcolumns are centrifuged, the RBCs pass through a viscous barrier into an active matrix containing proteins G and A. Positive tests adhere at the top of the gel and negative tests pass through, settling to the bottom. This study was undertaken to compare affinity column technology with low-ionic saline solution (LISS) tube tests in a reference laboratory setting. Over a 1-year period, 314 samples were tested in parallel by affinity column technology and by LISS tube technique. Both methods detected antibodies directed at common RBC antigens, high-incidence and low-incidence RBC antigens, and warm-reacting autoantibodies. IgM antibodies were not detected by affinity column technology. Affinity column technology compares favorably with the LISS tube technique for IgG antibody detection and identification.
