Reactivity caused by cold autoantibodies may mask the presence of alloantibodies. It may be necessary to remove the cold antibody from the serum. Rabbit erythrocyte stroma (RESt) can be used to remove Anti-I. Other techniques include prewarming and cold autoadsorption.
The prewarm method involves warming all testing components, such as patient sample, reagents, and saline, to 37°C prior to testing. The cold autoantibodies will not react and only clinically significant antibodies will react.
A cold autoadsorption that uses autologous cells could be performed to remove cold autoantibodies from the patient serum. The patient's cells are mixed with the patient's own serum and incubated at 4°C. Autoantibody is adsorbed onto the cells and alloantibody, if present, will remain in the serum. If the autoantibody titer is high, the adsorption may need to be repeated several times. This procedure should not be used if the patient has had a transfusion in the previous three months because donor cells may still be present in the circulation. If the patient has been recently transfused, RESt could be used. After the adsorption is complete, the serum/plasma can be tested against a panel of cells to determine if alloantibody is present.
