Development of human ABO blood group A antigen on Escherichia coli Y1089 and Y1090

Studies by other workers have shown that some strains of Escherichia coli have surface antigens analogous to the human blood group ABH antigens, and that these are carbohydrates associated with membrane lipopolysaccharides. This study has demonstrated that E. coli strains Y1089 and Y1090 possess the H antigen, which can be converted to the A antigen by incubation with A-transferase (N-acetyl-galactosaminyl transferase) and A-sugar (UDP-N-acetyl-galactosamine). Such cells will then form mixed agglutinates with human A red cells and human polyclonal (but not mouse monoclonal) anti-A antibodies. E. coli Y1089 and Y1090 have endogenous enzymes that use the A-sugar (in the absence of A-transferase) to produce a variant A antigen. Cells expressing this variant antigen adsorb anti-A antibodies but do not participate in mixed agglutination with human group A red cells. It is estimated that E. coli Y1089 and Y1090 possess approximately 5000 H epitopes per cell that can be converted to A epitopes.