Evaluation and comparison of four adsorption agents in removal of red cell autoantibodies

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Evaluation and comparison of four adsorption agents in removal of red cell autoantibodies

 

Author: Yan, Kin-fan
Title: Evaluation and comparison of four adsorption agents in removal of red cell autoantibodies
Degree: M.Sc.
Year: 1999
Subject: Hemolytic anemia, Autoimmune
Blood cells
Autoantibodies
Blood -- Transfusion
Hong Kong Polytechnic University -- Dissertations
Department: Multi-disciplinary Studies
Dept. of Nursing and Health Sciences
Pages: viii, 60 leaves ; 30 cm
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b1477329
URI: http://theses.lib.polyu.edu.hk/handle/200/4751
Abstract: Compatibility tests for patients with warm autoimmune hemolytic anemia are usually interfered by the red cell autoantibodies in serum. Such autoantibodies generally react with all red cell samples and mask the underlying alloantibodies. It is therefore prudent to remove the autoantibodies prior to alloantibody investigations. Removal of the autoantibodies is routinely done by adsorptions with autologous or allogeneic red cells which have been treated with ZZAP or protease reagent. However, it is practically difficult for blood bankers to obtain sufficient amount of red cells for this purpose, particularly when the patient has a low hematocrit or when allogeneic red cells of specific phenotypes are required. This study was conducted to evaluate and compare four different alternative adsorption agents, namely, formalin-fixed red cells, formalin-fixed platelets, digitonin red cell stroma, 3-phosphoglyceric acid and phosphocholine chloride bound on activated agarose column. They generally allowed ready accessibility to blood bankers. Evaluation was aimed to assess the non-specific uptake of red cell alloantibodies and efficiency in removal of the autoantibodies. Commercial polyclonal antisera and serum samples from 21 patients with warm autoimmune hemolytic anemia were used in the study. Digitonin red cell stroma gave the best performance among others. It did not show non-specific adsorption or 'Matuhasi-Ogata' uptake of red cell alloantibodies. Regarding efficiency of adsorption with the difficult samples tested, digitonin red cell stroma gave the highest success rate (86%), when compared with others, namely, conventional procedure (52%), formalin-fixed red cells (72%), 3-phosphoglyceric acid (62%) and phosphocholine chloride (57%). Digitonin red cell stroma can be stored at 1-6 C or -20 C for at least two months with no significant reduction in adsorption efficiency. This would much facilitate the stocking of selected donor red cell units for adsorption and allow the easy transfer of the reagents among blood centres and blood banks. The labor and time in the investigation of the alloantibodies would be saved and thus the blood delivery process would be speeded up. In addition, the risk of alloimmune hemolytic transfusion reaction due to masked alloantibodies would be reduced. Formalin-fixed red cells were not ideal as they caused slight non-specific adsorption of red cell antibodies. They were advantageous for being durable and reusable. No significant reduction in adsorption efficiency was detected after storage for two months or being repeatedly used for four times. Formalin-fixed platelets were considered unsuitable due to the marked non-specific adsorption of red cell antibodies. 3-Phosphoglyceric acid and phosphocholine chloride bound on activated agarose column were not satisfactory in terms of both effectiveness and efficiency. In conclusion, digitonin red cell stroma was a superior adsorption alternative to ZZAP- or protease-treated red cells in the removal of red cell autoantibodies.

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