The Warsaw Treaty Organization (also known as the Warsaw Pact) was a political and military alliance established on May 14, 1955 between the Soviet Union and several Eastern European countries.
1 Donors with blood type A... can donate to recipients with blood types A and AB. 2  Donors with blood type B... can donate to recipients with blood types B and AB.  Donors with blood type AB...
1 can donate to recipients with blood type AB only.  Donors with blood type O... can donate to recipients with blood types A, B, AB and O (O is the universal donor: donors with O blood are compatible with any other blood type)