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...
AB Negative. The rarest blood type, AB- is only found in 1 of every 167. AB- can give red blood cells to both AB- and AB+ recipients and can receive red blood cells from all negative blood types. AB- donors are encouraged to give platelet and plasma donations.