Why don't we incubate in DAT testing?

[studenttttttt 0]

What is the reason there is no incubation step for DAT?

[Malcolm Needs ★ 4,771]

The DAT is a test to detect either antibodies or complement (or both) on the surface of the red cells that has sensitised the red cells in vivo.  Therefore, in a way, the red cells have already been incubated within the body.  There is, therefore, no need to incubate ex vivo or in vitro, whichever way you want to put it.

[studenttttttt 0]

What would happen if you did? What's the chance you would get a false positive DAT?

[Malcolm Needs ★ 4,771]

It shouldn't cause a false positive, because the plasma would be from the patient, as would the red cells, and so they would be from the same source.  However, it is possible that the reaction may be enhanced by more antibody sensitising the red cells, but this would not be a false positive.

[SMILLER 864]

If one is doing a DAT in order to determine the status of a possible acute transfusion reaction, then the presence of antibodies on donor cells is the concern.  There may be some use in incubation here to enhance uptake, but I have never heard of it being part of anyone's transfusion work-up procedure.

Scott

[Dansket 428]

Incubating patient plasma with patient red blood cells and then applying the antiglobulin test is no longer a Direct Antiglobulin Test but an Autocontrol test which is an Indirect Antiglobulin Test.  Some may think an Autocontrol test gives the same results as a Direct Antiglobulin Test, but that is not always true.

 

[Malcolm Needs ★ 4,771]

Dansket is ABSOLUTELY right.