Alloantibodies
Alloantibodies are immune antibodies that are only produced following exposure to foreign red blood cell antigens.
- Produced by exposure to foreign red cell antigens which are non-self antigens but are of the same species.
- They react only with allogeneic cells.
- Exposure occurs through pregnancy or transfusion.
- Examples include anti-K and anti-E.
Autoantibodies
Some people develop antibodies that react with their own red blood cells. This autoimmune process can be a primary idiopathic condition or a secondary condition in patients with other conditions such as certain infections or lymphomas. Autoantibodies can be clinically significant and result in in vivo hemolysis, though many are considered benign. Autoantibodies typically react with all reagent cells as well which can cause serological complications during antibody screening procedures by masking any underlying alloantibodies.
- Produced in an autoimmune process and directed against one's own red cell antigens.
- React with patient's own cells and typically all cells tested.
- It is very important to make sure that no underlying significant antibodies are present if an autoantibody is suspected.
- A positive direct antiglobulin test (DAT) or autocontrol could indicate the presence of an autoantibody.
- Examples include cold auto (P or I) or warm auto (Rh specificity).
An
autocontrol is the patient's red blood cells mixed with their plasma/serum. A positive autocontrol suggests that the patient may have an autoantibody that is binding with their own red blood cell antigen. If the patient has an alloantibody, the autocontrol would remain negative.
