Comparative study between different alloadsorption techniques in warm autoimmune hemolytic anemia

Background Autoantibodies in patients with autoimmune hemolytic anemia (AIHA) are encountered with difficulties in ABO grouping and cross-matching; moreover, they may mask the presence of alloantibodies, leading to hemolytic transfusion reaction. Therefore, an efficient and time-saving method is required to detect alloantibodies underlying autoantibodies for safe transfusion in AIHA.Aim To compare the efficiency of different alloadsorption techniques in detection of alloantibodies after complete removal of autoantibodies.Patients and methods A total of 70 patients with warm AIHA were enrolled in this study; antibody screening was done by using screening cells (I+II+III cells). Allogenic adsorption was performed using conventional, polyethylene glycol (PEG), and low ionic strength solution (LISS)/papain methods followed by rescreening to ensure the adsorption of the autoantibodies, and whenever screening test revealed the presence of alloantibodies, antibody identification was done. Antibody identification and cross-matching with phenotyped red cells were done by the plasma obtained with this method. The best adsorption method was chosen depending on its ability to preserve the alloantibody.Results A significant difference was found among the three alloadsorption methods regarding number of alloadsorptions and time for complete autoantibodies removal. PEG showed the lowest mean number of alloadsorptions (2.6 +/- 1.2) followed by LISS/papain (3.1 +/- 1.5) compared with the conventional method (3.7 +/- 1.4) (P<0.001). Regarding the time, PEG was the most rapid method (38.6 +/- 17.6 min) followed by LISS/papain (45.9 +/- 22.8 min) and then the conventional method (110.1 +/- 14.4 min) (P<0.001). However, no significant difference was found between PEG and LISS/papain (P=0.014). Alloantibodies were detected in 35% of cases, with predominance of anti-Rh system (61%), mainly anti-c and anti-E. Alloantibodies belonging to Rh and Kidd were best identified in adsorbed plasma by LISS/papain in comparison with PEG and the conventional techniques.Conclusion Among the evaluated methods, LISS/papain displayed the highest diagnostic accuracy, sensitivity, and specificity of alloantibody detection. Compared with the conventional method, LISS/papain and PEG minimized the time and number of alloadsorptions, enhancing turnaround time and reducing the labor of pretransfusion testing in AIHA.