When is it appropriate to perform an elution on a patient with a postive DAT? I know if a patient's DAT is postive with Anti-IgG and he has been transfused withing the last month then an elution is done. But I am a little confused when it comes to DATs postive only with anti C3. I have read that elutions are also appropriate but I am not quite sure why since it would be negative. Can anyone offer an explanation? Thanx

If any of our DATs are positive with only anti-C3 then we do not perform elutions

We perform eluates only on cells with IgG on them.

I suppose you might be able to elute an IgG antibody on a cell reactive with Anti-C3 only, and maybe concentrate enough of it to identify it, but the probability of such a thing would be very, very small ...

If you strongly suspect a new antibody formed due to recent transfusion that might be mostly IgM (c3) but possibly starting to make IgG which would all be stuck to the transfused cells in circulation, then it might be worth doing an eluate, but otherwise, we wouldn't.

I have actually found the rationale behind performing an elution on DATs positive with only anti C3. Anti Jka is a strong activator of complement so some patients that are making anti Jka will actually have cells mostly coated with C3 but also with some anti Jka (IgG variety) early on in their immune response. The textbook (Fundamentals of Immunohematolgy. Turgeon, 1995.) I found this in states that if only the C3 is positive and the patient has recently been transfused then antigen type the patient for Jka. If negative then an elution is appropriate. I suppose they antigen type the patient using retics since typing the cells in a recently transfused patient is unreliable.