Girl Switches Blood Type

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I've read in Yahoo news that an australian girl has swithced blood type after a liver transpant. This is the first and only case that this happened. We all know that the immune system would reject blood cells that is different from the host. So how did this happen? But my main question is, how could it happen that a liver from a donor of a different blood type was transplanted into a girl? Was it just experiment that maybe it would work out this time? Apparently not. Then why?