Type O Blood – comprises approximately 45% of the US population. Type O RBCs do not express A and B antigens, which is what makes it the ‘Universal Donor’ type. Type O blood contains both anti-A and anti-B antibodies in the plasma. Type O patients can only receive Type O WB or LTOWB.

Type A Blood – comprises 40% of the US population. Type A individuals express the A antigen on the RBCs and anti-B antibodies in the plasma. Type A patients can receive Type A WB or LTOWB.

Type B Blood – comprises 10% of the US population. Type B individuals express the B antigen on the RBC and anti-A antibodies in the plasma. Type B patients can receive Type B WB or LTOWB.

Type AB Blood – comprises just 5% of the US population. Type AB RBCs express both Type A and Type B antigens and therefore do not have circulating anti-A or anti-B antibodies in their plasma. This makes Type AB the ‘Universal Recipient’ for RBCs and the universal donor for plasma because their plasma does not contain anti-A or anti-B. Type AB patients can receive Type AB WB or LTOWB.