title: Subgroups A1 and A2: qualitative and/or quantitative distinctions?
mesh_terms: D000017:ABO Blood-Group System / Q000032:analysis* / Q000276:immunology; D000373:Agglutinins / Q000276:immunology; D000937:Antigen-Antibody Reactions; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D007106:Immune Sera
chemical_list: D000017:ABO Blood-Group System; D000373:Agglutinins; D000939:Epitopes; D006023:Glycoproteins; D007106:Immune Sera