Comparison of affinity column technology and LISS tube tests

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.