Definition: a method designed to remove antibody from serum by incubating it with red cells positive for the corresponding antigen.
Removing autoantibody activity to permit detection of possible coexisting alloantibodies. For example, if a patient has an autoanti-1, an autoadsorption at 4°C can be done to remove it, and the autoadsorbed serum can be run against a panel to identify any possible alloantibodies present.
Reagent preparation: removing anti-A or anti-B or other unwanted antibodies from serum that contains an antibody suitable for reagent use, e.g., serum from a group A donor containing anti-D can be adsorbed with group B Rh(D) negative blood cells: the anti-B will be adsorbed, but the anti-D will not.
Separating multiple antibodies to aid in identification: for example, if you suspect a serum contains anti-c and other unidentified antibodies that react with R1R1 cells, you could adsorb the serum with R1R1 cells. Anti-c would remain free in the supernatant and could be confirmed by testing the supernatant with panel cells. The antibodies which attached to the R1R1 cells could be eluted and identified.
Note: adsorptions are often done in conjunction with elutions
Confirmation of the presence of a weak antigen on red cells: this can be done by proving their ability to adsorb and remove specific antibody. For example, supposing a patient's ABO group gave the following results:
| anti-A | anti-B | A1 cells | B cells |
|---|---|---|---|
| -- | -- | -- | 4+ |
The patient may be a group A with a very weak A antigen (weak subgroup of A). His red cells could be incubated with anti-A at 4°C for an increased time (e.g., 4 - 12 hours) and then an elution could be prepared. If the eluate contain anti-A, it is possible to conclude the A antigen must have been on the red cells.
Confirmation of antibody specificity: if you suspect a serum contains an antibody (e.g., anti-c) plus one or more antibodies (e.g., anti-K and anti-Fya), you can confirm the anti-c by doing an adsorption followed by an elution, e.g., incubate serum with red cells that are Fya-, K-, but c positive, then do an elution of the adsorbed cells and test it with panel cells to confirm it contains anti-c.
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| Adsorptions |
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