The serum/plasma reactivity can be indicative of the type of autoantibody present. The tests/procedures listed in Table 2 below can be used to detect the presence of an autoantibody and differentiate between the types of autoantibodies.
Table 2. Autoantibody Testing.Test
| Use
| Result
| Comments
|
Antibody Screen
| Determine the antibody present in serum/plasma
| If there is reactivity with all cells tested, including an autocontrol, an autoantibody is likely.
| The phase of reactivity can determine if it is a cold-reactive or warm-reactive autoantibody. If there is a specificity noted (e.g., PCH antibody with P antigen specificity), a more specific determination of the autoantibody can be made.
|
Direct Antiglobulin Test (DAT)
| Detect in vivo sensitization of red blood cells
| Usually positive if an autoantibody is present.
| Using monospecific antiglobulin reagents (IgG and Complement AHG reagents) can differentiate between IgM and IgG antibodies and determine if complement is involved.
|
Elution
| Remove antibody from sensitized cells to determine antibody specificity
| If warm-reactive, IgG autoantibodies are present, the eluate will be reactive with all cells.
| Red cells must be thoroughly washed with normal saline, buffered saline, or low ionic strength saline (LISS) prior to an elution procedure to ensure that the antibody recovered represents only that antibody bound to red cells, not “free” antibody in the plasma or serum.
|
