Naturally occurring ABO antibodies are IgM by nature.
IgM antibodies react better at colder temperatures.
When encountering Group I ABO typing discrepancies, it can be effective to incubate patient plasma and reagent red cells at room temperature or 4°C to enhance the potential of reactivity.
Room Temperature Incubation
- Incubate patient plasma and reagent red cells at room temperature for 15 to 30 minutes.
- Centrifuge sample and examine for macroscopic agglutination.
- If unresolved, proceed to incubation at 4°C.
4°C Incubation
- Incubate patient plasma and reagent red cells at 4°C for 15 minutes.
- To ensure that no underlying cold reacting antibody interferes with the reaction, an auto control and O cell control should be included.
- Auto control is used to screen for a cold reacting autoantibody.
- O cell control is used to screen for a cold reacting alloantibody.
- After a 15 minutes incubation, centrifuge and read for macroscopic agglutination.
