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.

  • $\begingroup$ Can you please give a reference for this happening? $\endgroup$
    – Chris
    Commented Feb 26, 2015 at 17:33
  • $\begingroup$ This is particularly true for the marmoset. Recent research shows most marmosets are chimeras, sharing DNA with their fraternal twins.[5] 95% of Marmoset fraternal twins trade blood through chorionic fusions, making them hematopoietic chimeras.[6][7] $\endgroup$
    – curiousman
    Commented Feb 26, 2015 at 17:35
  • $\begingroup$ @Chris Taken from wiki page for chimerism $\endgroup$
    – curiousman
    Commented Feb 26, 2015 at 17:37
  • 1
    $\begingroup$ If they have both antigens from the beginning, they won't develop antibodies to them. $\endgroup$
    – canadianer
    Commented Feb 26, 2015 at 17:42
  • 5
    $\begingroup$ That's like people who have bloodgroup AB - if they have this from the beginning, they develop no antibodies. $\endgroup$
    – Chris
    Commented Feb 26, 2015 at 18:30

1 Answer 1


Since these cells are there by the development of the immune system, the immune cells recognize them as self. By blood transfusion with incompatible blood type, the immune system recognizes the blood cells with different histocompatibility antigens (A,B,Rh etc...) as non-self, that's why it attacks them.


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