Cold antibody
- Immediate spin screen and panel cell reactions will be positive (W+ to 4+). The autocontrol may also be positive.
- AHG reactions may be weakly positive if the cold antibody is bound strongly to the red cells.
- Prewarming should prevent binding from occurring.
Warm antibody
- Immediate spin reactions on the screen cells, panel cells, and autocontrol are usually negative.
- AHG reactions will be positive including autocontrol (W+ to 4+).
- Prewarming of sample and reagents will not change positive reactions since they react best at 37°C and AHG phase. So, reactions will still be positive.
- Elution and autoadsorption techniques may be used to help further identify the antibody or to help identify other clinically significant antibodies that may be present.
Autoadsorption
Autoadsorption is a technique that involves adsorbing unbound autoantibody from the patient's serum using the patient's own red cells. Once the autoantibody is removed, then testing can be performed to determine if any clinically significant antibodies are present. This is only possible when the patient has not been recently transfused. If donor cells are still in circulation, alloantibodies may also be adsorbed. In these cases, phenotypically similar reagent cells may be used for an alloadsorption procedure.
