Why can people with blood group ab receive from other groups but cannot donate to them?

People with blood group AB can receive blood from any blood group (A, B, O, or AB) but can only donate to people with blood group AB. This is because:

- AB plasma lacks anti-A and anti-B antibodies. This means that people with blood group AB can receive blood from any blood group without their immune system attacking the donated red blood cells.

- AB red blood cells have both A and B antigens on their surface. This means that people with blood group AB can only donate blood to people with blood group AB. People with other blood groups (A, B, or O) have antibodies against either the A or B antigen, which would attack the donated AB red blood cells.