Cell and Organ Transplantology. 2025; 13(1):22-31 (e2025131180).
DOI: 10.22494/cot.v13i1.180

Comparison of agglutination and adsorption activities of blood group typing antibodies under different pH and temperature conditions

Kravchun P.¹, Dunayeva I.¹, Leontyeva F.², Povelychenko O.², Kadykova O.¹, Borzova-Kosse S.¹, Dielievska V.¹

• ¹Kharkiv National Medical University, L. T. Malaya Department of Internal Medicine No. 2, Clinical Immunology and Allergology, Kharkiv, Ukraine
• ²Sytenko Institute of Spine and Joint Pathology, National Academy of Medical Sciences of Ukraine, Kharkiv, Ukraine

Abstract

Blood group compatibility is essential for the success of organ transplantation and for reducing the risk of rejection. Studying the optimal conditions for the interaction between blood group-specific monoclonal antibodies and erythrocytes plays a crucial role in accurate blood typing for cell and organ transplantation.
Aim. This study is aimed to evaluate the agglutination and adsorption activities of blood group-specific IgM and IgG antibodies under varying pH and temperature conditions.
Materials and methods. The agglutinating and adsorbing properties of monoclonal antibodies of IgM and IgG isotypes with different isoelectric points were analyzed after incubation with red blood cells (RBCs) under various pH values (6.0, 7.4, 7.8) and temperatures (4  °C and 37  °C). Washed group A red blood cells (RBCs) from healthy volunteers (n = 99) were incubated with a panel of IgM and IgG monoclonal antibodies, including 2-8, 2-10, 2-19 (acid-type anti-A Mabs), 2-23 (alkaline-type anti-A Mabs), and anti-H BRIC-231. Agglutination strength was evaluated microscopically and graded on a scale from 0 to 4. Adsorption activity was assessed by analyzing residual antibody activity in the supernatant after incubation.
Results. For IgM of alkaline type and IgG3 antibodies, with optimal adsorbing activity in alkaline medium at 4 °C, maximal adsorbing activity at 37 °C was detected in acidic medium. IgM Mabs exhibited stronger agglutination at 4  °C compared to IgG3 Mabs. Polyclonal antibodies, conventional IgM, and acid-type IgM Mabs demonstrated higher agglutination at pH 7.8, in contrast to alkaline-type IgM and IgG3 Mabs. The optimal temperature for maximal adsorption activity corresponded to the temperature that yielded the strongest agglutination. However, the optimal pH for adsorption was generally opposite to that for agglutination.
The adsorption of IgM antibodies was pH-dependent. Specifically, at 4  °C, the highest adsorption of conventional and acid-type IgM antibodies occurred at pH 6.0, while at 37  °C, it was observed at pH 7.8. For alkaline-type IgM and IgG3 antibodies, optimal adsorbing activity occurred in alkaline medium at 4 °C, whereas at 37 °C, maximal adsorbing activity was observed in acidic medium.
Conclusion. The agglutination and adsorption properties of blood group-specific IgM and IgG antibodies are influenced by both pH and temperature, with their optimal pH values differing for these two functions. For the detection of weak A and B antigen variants via adsorption assays at 4  °C, pH 6.0 is recommended for IgM antibodies, while pH 7.8 is preferable for IgG antibodies.

Key words: blood group compatibility; red blood cells; agglutination; adsorption; IgM; IgG

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