Pos DAT in patient with autoimmune process

[kirkaw]

Hi All,

A rheumatologist ordered a DAT on a patient last night. The Polyspecifc, IgG and C3 were all positive. The patient's last transfusion was in Jan. 2012. The antibody screen is negative. The eluate yielded a sort of mixed field panagglutinin in gel. From previous posts, it seems like the most likely reason for the mixed field is junk.

This patient has an elevated sed rate and a positive RF. The rheumatologist has ordered a bunch more sendout tests, including anti-double stranded DNA.

So, I am thinking this is most likely an autoimmune thing. Would you recommend any further testing? If so, what? Is there evidence that a patient with these sort of processes going on would have a positive DAT? Is it considered clinically significant?

Thanks!

[Malcolm Needs ☆]

RA is an auto-immune disease. Ordering double-stranded (and, come to that, single-stranded) DAN is a reasonable request.

Blood transfusion-wise, no further testing is required (although they do tend to have pan-agglutinating anti-kappa, anti-lambda, anti-Gm, etc antibodies - but these are "so what" antibodies, as far as blood transfusion is concerned).

THe DAT, in terms of blood transfusion, is clinically insignificant.

[Mabel Adams]

People with autoimmune diseases like RA and Lupus are more likely to make autoantibodies. Was the saline control run with the DATs negative?

[JOANBALONE]

I may not consider the mixed field pan agglutinin as junk. I would consider it an autoantibody most probably due to autoimmune disease. I would report an eluate positive with all cells. You mentioned that the antibody screen is negative so I would not perform additional testing. I agree with Malcolm, in terms of transfusion it is not considered clinically significant.

[Rh-fan]

I may not consider the mixed field pan agglutinin as junk. I would consider it an autoantibody most probably due to autoimmune disease. I would report an eluate positive with all cells. You mentioned that the antibody screen is negative so I would not perform additional testing. I agree with Malcolm, in terms of transfusion it is not considered clinically significant.

I hope that Malcolm and you are talking about this, not recently transfused, patient.

In patients that have been transfused (the last 3 months) a positive DAT can be clinical significant for transfusion.

Peter

[Malcolm Needs ☆]

Good Lord YES Peter - I am talking about this patient!!!!!!!!!!!!

[JOANBALONE]

Me too.

[Mabel Adams]

I am going to throw out a weird idea here. We were working on a patient recently that had a lot of non-specific reactivity in gel so we were looking up what was in the gel panel cell diluent vs what was in the 3% panel cell diluent. I was interested to note that both the gel diluent and 3% diluent contain purines and nucleosides (and one of them has steroids). I had to look up their definitions to be reminded that they are the the building blocks of DNA or RNA. So...if your patient ends up having antibodies to DNA could it be reacting somehow with the purines and nucleosides in the gel diluent??? I have no idea. I just saw a possible connection here. Oh, wait, you had reactions only in the eluate and these antibodies couldn't attach to the patient's cells, I suppose. But this is such an interesting observation (the contents of gel diluent) and I have already typed so much, I think I will leave this post.