Warm Autoadsorption: Are We Wasting Our Time?

BACKGROUND: Our current adsorption procedure follows the accepted practice of adsorbing autoantibodies from patient’s serum up to three times with either ZZAP-pretreated patient red blood cells (RBCs) and/or ficin-pretreated allogeneic RBCs. This time-consuming process can require up to six hours, which may create significant delays that can impact patient care. The aim of this study was to modify the current adsorption method to reduce the total adsorption time to one hour. STUDY DESIGN AND METHODS: A ratio of one part patient serum to three parts RBCs (1:3 Method) was maintained for all samples. The one part of patient serum was first split into three separate tubes. Each aliquot of patient serum was mixed with one full part of ficin-pretreated allogeneic RBCs, creating three separate adsorbing tubes each containing 1 part patient serum and three parts RBCs. All tubes were incubated for one hour at 37°C with periodic mixing. The adsorbed serum from each tube was harvested and combined into one tube and tested with the originally tested selected panel cells, if available, in the same phases that showed reactivity. If the originally absorbed serum did not exhibit underlying alloantibodies when tested with a full panel of cells, the newly adsorbed serum was only tested with a three-cell antibody screen. RESULTS: A total of 58 patient samples known to contain warm autoantibodies were evaluated using the current method and the modified 1:3 Method. Forty-eight cases (83%) were successfully adsorbed using both methods. Of these 48 cases, 20 (34.5%) contained underlying alloantibodies. In all 20 cases with underlying alloantibodies, the 1:3 Method demonstrated the same antibody specificities and reaction strengths as the current method. Eight cases failed to be adsorbed by both the current method and the 1:3 Method and required allogeneic adsorption using Polyethylene Glycol (PEG). The 1:3 Method detected underlying alloantibodies in three cases (two anti-E, one anti-f) that were not detected using the current method. Two cases successfully autoadsorbed but failed to alloadsorb by both methods. CONCLUSION: The 1:3 adsorption method proved to be efficient as well as effective for quick removal of autoantibodies while allowing for the detection of underlying alloantibodies. Moreover, the 1:3 adsorption method demonstrated equal or comparable results to the currently accepted adsorption method in a total adsorption time of only one hour.