ABO Antibodies and Their Development

Humans develop anti-ABO antibodies, particularly IgM, early in life without prior exposure to different blood types. This phenomenon is believed to have evolutionary benefits, as it provides a defense mechanism against pathogens that may exhibit similar carbohydrate structures to the ABO antigens. Research suggests that exposure to certain foods, particularly legumes, along with interactions with gut microbes, may contribute to the formation of these antibodies. Consequently, by six months of age, around 80% of babies have developed these antibodies, highlighting a crucial aspect of human immunology tied to both physiology and evolution.