Naturally occurring ABO antibodies (anti-A and anti-B) are primarily of the IgM class. A key characteristic of IgM antibodies is that they are large, pentameric molecules that generally do NOT cross the placenta from mother to fetus. The placenta selectively transfers IgG antibodies. Therefore, while ABO hemolytic disease of the fetus and newborn (HDFN) can occur, it is usually mild because the causative antibodies are the mother's IgG anti-A or anti-B, which are not the classic 'natural' IgM antibodies but rather immune IgG responses that some individuals develop. The statement that ABO antibodies 'cross the placenta readily' is incorrect for the primary IgM antibodies. They are, however, naturally occurring, stimulated by bacteria, strongly reactive at 37°C, and capable of binding complement.

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Zambia

• ivwananji siwale – 29 pts

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