ABpositive

ABpositive, commonly written as AB+ or AB, is a human blood type within the ABO and Rh blood group systems. It is defined by the presence of both A and B antigens on red blood cells and the D antigen of the Rh system, making the individual Rh positive. People with AB+ blood have no anti-A or anti-B antibodies in their plasma under normal conditions, which allows them to receive red blood cells from any ABO type. They are described as universal recipients for red blood cells, though they can donate RBCs only to other AB+ recipients.

The AB phenotype results from co-dominant IA and IB alleles, inherited from one’s parents, along with at least one copy of the RhD gene. The Rh factor is inherited separately, with D being the common determinant of positivity.

Prevalence of AB+ varies by population, but it is typically around 4–7% of people in many populations.

In transfusion medicine, AB+ status informs donor–recipient matching. For red blood cell transfusions, AB+ recipients can receive from any ABO type, while AB+ individuals can donate only to AB+ recipients. For plasma transfusions, AB plasma is compatible with recipients of any ABO type because it lacks anti-A and anti-B antibodies. Rh status is generally less critical for plasma compatibility, though it may be considered in certain clinical contexts.

ABpositive can also be used as a branding or organization name, but in medical contexts it refers to the AB positive blood type.