Description : Why does A+ and O+ blood types do not match for blood donating?
Last Answer : Generally, if you have O+ blood, you should be able to donate to someone with A+ blood (O+, B+, and AB+ as well). However, blood from someone of the same blood type is preferred, so ... A antigens in type A blood, so if they received a transfusion, their blood would react and agglutinate (clump).