Humans are not born with anti-A and anti-B antibodies; they develop them in the first few months of life. The primary stimulus is exposure to certain bacteria that are part of the normal intestinal flora. The surfaces of many common bacteria (e.g., E. coli) contain polysaccharides that are structurally very similar to the A and B blood group antigens. When an infant whose red cells lack, for example, the B antigen is colonized by bacteria carrying B-like substances, their immune system mounts a response, producing antibodies (IgM) against that bacterial antigen. These antibodies happen to cross-react with human B antigens, resulting in the production of 'natural' anti-B.

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Zambia

• ivwananji siwale – 29 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies