Quick answer
AB positive (AB+) means red blood cells carry both A and B antigens as well as the RhD antigen. Because AB+ plasma generally lacks anti-A, anti-B, and anti-D antibodies, AB+ people can generally receive red cells from all eight common types. AB+ red cells can generally be given only to AB+ recipients.
What AB+ means
AB indicates both A and B antigens are present on red cells. Plasma from AB people typically contains neither anti-A nor anti-B antibodies.
This lack of ABO antibodies is why AB+ is often described as the universal red cell recipient. Rh-positive status means Rh-positive or Rh-negative red cells are both generally acceptable.
Because AB red cells carry both antigens, they are only compatible with AB recipients. AB plasma, however, is broadly compatible and is considered the universal plasma type.
| Property | Value |
|---|---|
| ABO group | AB |
| Rh (D) status | Positive (RhD antigen present) |
| Red cell antigens | A, B, RhD |
| Plasma antibodies (typical) | None (ABO) |
Compatibility summary
General red cell and plasma compatibility for AB+ under the simplified ABO/Rh model. Real transfusions also depend on antibody screening and crossmatching.
| Product | Can give to | Can receive from |
|---|---|---|
| Red blood cells | AB+ | O−, O+, A−, A+, B−, B+, AB−, AB+ |
| Plasma (ABO only) | A, B, AB, O | AB |
See the full compatibility chart for all eight types.
Inheritance context
Type AB has only one genotype under the standard model: one A allele and one B allele. This means one parent contributed A and the other contributed B.
An AB child cannot have a type O parent under the standard model, because a type O parent (OO) cannot pass on A or B. Rare exceptions such as cis-AB exist.
Two AB parents can have A, B, or AB children (25%, 25%, 50%) but not type O children.
Work through specific parent combinations with the baby blood type calculator, or find which parent types could produce a AB+ child with the parent calculator.
Limitations
- Blood type can only be confirmed by laboratory testing. Family history, calculators, and self-report are not substitutes.
- Compatibility rules on this page are general educational summaries. Real transfusion decisions also depend on antibody screening, crossmatching, product type, and clinical judgment.
- Rare variants such as the Bombay phenotype, cis-AB, and weak or partial D expression can produce results that differ from the simplified ABO/Rh model.