If a person is a chimera and has two different blood types in his veins, how does he not die? Shouldn't the immune system attack one of the blood types?
In 1953 a human chimera was reported in the British Medical Journal. A woman was found to have blood containing two different blood types. Apparently this resulted from her twin brother's cells living in her body. More recently, a study found that such blood group chimerism is not rare.