Prevalence of unexpected red blood cell antibodies in blood donors

Abstract

Red blood cell (RBC) antibody screening is an obligatory part of our national blood testing strategy. It has been performed on regular basis, on every donation from each donor. In the last decade we have introduced more sensitive methods for detecting RBC antibodies. Aim of the study: To estimate the prevalence and the nature of the irregular RBC antibodies detected in the period from 2009 to 2014 and to analyze demographic characteristics of blood donors with specific antibodies. Material and methods: A total of 158170 blood units were screened for irregular RBC antibodies using pooled screening cells (2 donors) in combination with the indirect antiglobulin test (IAT), performed by gel technique and the automated system Techno Twin Sampler. Samples with confirmed positive antibody screening were subjected to antibody identification with commercial red cell panels (DiaMed and Ortho). We used blood donor data from the donor information system. Results: The total number of samples with positive antibody screening was 122 (0.078%). The ratio of female to male donors with positive antibody screening was 64 (52%): 58 (48%) respectively. Specific antibodies were identified in 67 (55%) out of 122 samples from which 53 (79.1%) were clinically significant (CS). The overall prevalence rate of the specific antibodies was 0.04%. The specificity of antibodies was as fallows: anti-D, 15 (22%); -E, 11 (16%); -C, 4 (6%); -c, 3 (4.5%); -Cw, 2 (3%); -K, 13 (19.5%); -Kpa, 2 (3%); -Fya, 1 (1.5%); -Lua, 2 (3%); -M, 11 (16.5%); -P, 2 (3%) and anti-Leb, 1 (1.5%). The average age in donors with CS antibodies was 48.2 years. The average number of donation prior to the antibody detection was 1.7 with mean interval between donations of 1.8 years. Conclusion: The prevalence of RBC irregular antibodies in our blood donors is very low mainly due to the good donor selection programme, as well as to the currently used screening method which contributes to the decrease of false positive and nonspecific reactions. The low prevalence of antibodies raises the question of cost-effectiveness of red cell antibody screening on regular basis. However, permanent donor education and further analysis of the possible impact on the safety of our blood supply is essential to establish cost-effective and safe RBC antibody screening model by targeting of donors which are at particular risk of RBC alloimmunization.