In allogeneic adsorption, pre-selected donor cells are used to adsorb the autoantibody from the patient's serum. The adsorbed serum can then be tested against donor reagent cells to identify an alloantibody, if present.
Alloadsorption. (6)For patients with a known phenotype:
To determine the cells to perform the adsorptions, cells that are phenotypically similar are used to rule out alloantibodies the patient is capable of making. For example, if the patient is K negative, you want to use a cell that is K negative to adsorb the serum. This allows an anti-K to remain in the sera if present.
Aliquots of allogeneic cells are available and typically consist of R1R1, R2R2, and rr phenotypes. Depending on the patient's phenotype, you may need 1 of the aliquots or all 3. Multiple aliquots are often required to rule out antibodies that the patient is capable of forming. Each aliquot will be used to rule out different antibodies.
For patients with an unknown phenotype:
All aliquots will be used to perform the adsorption and rule out as many alloantibodies as possible. Multiple adsorptions will likely need to be performed. As a general rule of thumb, the strength of the DAT indicates how many adsorptions will need to take place. For example, a DAT with the IgG phase having a 3+ reaction will generally require at least 3 adsorptions.
To determine if enough adsorptions are done, a DAT will be performed. If the IgG component is negative, the adsorptions were successful and the adsorbed sera can be used for further testing.
