Prevalence of natural ABO antibodies in donors in Surgut

BACKGROUND: The physiological status of a population can be assessed through the adaptive function of maintaining internal homeostasis, particularly by studying the activity of natural antibodies. The population-specific ecological variability in antibody production is of interest for both population physiology and the advancement of applied transfusion medicine and transplantation. AIM: To assess the prevalence of natural ABO antibody titers in donors in Surgut. METHODS: A single-center, cross-sectional, observational study was conducted. The study included donors from Surgut. The presence and activity of natural complete ABO anti-erythrocyte α (anti-A) and β (anti-B) antibodies were assessed using slide titration with standard A(II) and B(III) erythrocytes and isotonic sodium chloride solution. The prevalence of antibody titers was calculated as a percentage. RESULTS: A total of 14,223 donor blood samples were analyzed. In type O(I) blood donors, natural antibody activity began at titers of 1:2 and 1:4, with some reaching titers as high as 1:512. The most prevalent titers in type A(II) blood donors were 1:8 in males and 1:16 in females, whereas in type B(III) blood donors, a 1:32 titer was most common in both sexes. The highest titers reported in the A(II) and B(III) groups were 1:256. Titer distributions were similar in males and females, with an overall tendency toward lower titers in 2023. A high incidence of 1:8 and 1:16 titers was reported in males and females, respectively. CONCLUSION: Distinct patterns in the prevalence of natural ABO antibody titers were identified in 2015–2017 vs. 2023, a period with post-COVID-19 immune response transformation. These differences are likely due to previous SARS-CoV-2 infection and its effects on immune system function. The findings indicate that Surgut donors' immune systems actively produce natural ABO antibodies, which is important for assessing the physiological structure of populations living in specific environments.