The answers to this question are wrong. AB blood type can only donate to AB do to the facts that both A and B have antigens around they surface that will cause other blood type to form antigens that will attacks that type blood. However, AB blood type is a universal recipient.
AB is a universal receiver therefore it can receive of A,B,AB,O but can only donate to AB. AB has antigens A and B and no antibodies. So if it is given to anyone other than AB an immediate immune response would occur