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...
can donate to recipients with blood types B and AB. Donors with blood type AB... 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)