Single-strained DNA aptamers mask RhD antigenic epitopes on human RhD+ red blood cells to escape alloanti-RhD immunological recognition

Rhesus D- (RhD-) individuals should receive Rh-matched blood to prevent hemolytic anemia. However, there is a shortage of RhD- blood. This study aimed to generate RhD antigen-specific single-stranded DNA (ssDNA) aptamers, and test their efficacy in masking RhD antigens on RhD+ red blood cells (RBCs) to prevent their immunoreactivity in vitro. In the present study, ssDNA aptamer candidates were synthesized as a central randomized sequence of 40 nucleotides (nt) flanked by 21-nt primer hybridization sequences. The functional aptamers were screened using the cell-based systematic evolution of ligands by exponential enrichment technique and RhD+ RBCs. Two bioactive ssDNA aptamers significantly inhibited the binding of an anti-RhD antibody to RhD+ RBCs and bound to RhD antigens with high affinity (dissociation constant values of 580.5 +/- 142.0 and 737.7 +/- 161.8 nM, respectively). Furthermore, treatment with both ssDNA aptamers (500 pmol) effectively masked RhD antigens on 4,000,000 RhD+ RBCs to prevent human anti-RhD alloantibody-mediated binding, RBC agglutination and monocyte recognition in vitro. Collectively, such data suggested that these ssDNA aptamers may be feasible for masking RhD antigens on RBCs, and thus valuable for prevention or at least amelioration of RhD+-related hemolytic anemia in RhD- individuals.