I think this is the thread you are looking for:
Extraterrestrial Threat to those with negative blood types?
Another one on that topic here:
Negative Blood Type (RH Factor) and Alien History
Edit: Just noticed that you were not actually asking for that thread. My bad. And I think I am AB.
edit on 19-5-2011 by InvisibleAlbatross because: (no reason given)