Positive with gel cards negative with tube

[Desoki]

Two days before, I had a case referred from one colleague, this case was for female patient with sickle cell anemia age 18 year with previous transfusion, now patient is positive antibody screen with three cells of Diamed gel cards and when I did panel identification by Diamed gel cards the result was 8 cells of 11 panel cells were positive with different strength and autocontrol positive and DAT positive, but these positive cell didn’t lead me to any result so I tried to use another panel but only available other panel was for Biotest company but not gel, tube, unfortunately when I read the result of tube panel all cells became negative, tube antibody screen negative even tube autocontrol negative also crossmatch with units by tube also negative I comfirmed all the result s by coombs check cells, all negative give positive with CCC.

My explanation is patient has something against gel or Liss in gell cards……….!!!!!!!!!!

Do you have any explanation?

[Malcolm Needs ☆]

Sorry Mohammad, but when you say that she has received a transfusion, who recently? This is very important.

[Desoki]

Sorry Mohammad, but when you say that she has received a transfusion, who recently? This is very important.

yes Malcolm but may be I heard wrong from my collague, I asked her again now but this patient didn't receive blood since last two years

[Malcolm Needs ☆]

Good, thanks for that.

Probably what has happened is that the patient has produced a very weak auto-antibody, which is so weak that, when you perform a tube technique, the antibody is washed off the red cell surface during the washes after the incubation, so that you do not detect it by tube technique.

However, when you use the column agglutination technology, there is, of course, no washing phase, and so the weak antibody remains on the red cells, and so you are able to detect it by CAT.

I just wanted to make sure that the young lady hadn't been transfused recently and was beginning to make an auto-antibody (with the auto and DAT looking positive, because the new antibody was sensitising the transfused red cells).

[Rh-fan]

Good, thanks for that.

Probably what has happened is that the patient has produced a very weak auto-antibody, which is so weak that, when you perform a tube technique, the antibody is washed off the red cell surface during the washes after the incubation, so that you do not detect it by tube technique.

However, when you use the column agglutination technology, there is, of course, no washing phase, and so the weak antibody remains on the red cells, and so you are able to detect it by CAT.

I just wanted to make sure that the young lady hadn't been transfused recently and was beginning to make an auto-antibody (with the auto and DAT looking positive, because the new antibody was sensitising the transfused red cells).

You mean allo ??

[Auntie-D]

Have you checked the tube under the microscope to see if there is agglutination but you just can't see it?

[Malcolm Needs ☆]

You mean allo ??

Yes I do Peter - sorry about that!

[Desoki]

Have you checked the tube under the microscope to see if there is agglutination but you just can't see it?

No, I didn't check under microscope, I just comfirmed by CCC

[Yanxia]

You mean allo ??

Maybe I miss something, but I think it is auto. Because the pos DAT and autocontrol and more than 2 years not been transfused.

[Malcolm Needs ☆]

Maybe I miss something, but I think it is auto. Because the pos DAT and autocontrol and more than 2 years not been transfused.

No, it is allo.

What I was trying to get at was that, if the patient had recently been transfused, both the auto and the DAT could have been positive, because a "new" antibody could have been forming, and was, therefore, on the circulating transfused red cells, but was not yet strong enough to have the transfused red cells removed from the circulation.

The typo was definitely my fault!!!!!!!!!

[Malcolm Needs ☆]

Hmmm. I think I could have put that a little bit/a lot better!

What I meant was that I meant "allo" in my post, but that, as a result of the patient not having been transfused for such a long time, the positive auto and the DAT must be due to an auto-antibody.

[Julie Shannon]

Another possibility would be the IgG4 component on the rabbit blend IgG used on the gel cards. This would only hold true if the tube testing was performed with a different source of IgG. We have seen that in our reference lab setting. We prove this by repeating our tube testing using the Ortho IgG.

[galvania]

Mohammed - if you had 8/11 cells positive in the panel, you have something specific. This cannot just be an anti-buffer or anti-gel. It may or may not be significant. You can try some simple things to see if you get better differentiation. Firstly, have you checked to see if the reaction matches with homozygous cells only? Also, if you have recourse to enzyme-treated red cells, then you can use these cells on Coombs cards and see if that helps. Kidd antibodies will come up well this way. Also, try incubating your Coombs cards at room temperature - I know that sounds strange, but sometimes this is helpful if you have an anti-M or N, or even sometimes S/s. Otherwise, if you give me the lot number of the panel cells and tell me which cells were positive - a picture would be even better - I can see if I can make sense of the reactions for you

Anna

[Desoki]

Mohammed - if you had 8/11 cells positive in the panel, you have something specific. This cannot just be an anti-buffer or anti-gel. It may or may not be significant. You can try some simple things to see if you get better differentiation. Firstly, have you checked to see if the reaction matches with homozygous cells only? Also, if you have recourse to enzyme-treated red cells, then you can use these cells on Coombs cards and see if that helps. Kidd antibodies will come up well this way. Also, try incubating your Coombs cards at room temperature - I know that sounds strange, but sometimes this is helpful if you have an anti-M or N, or even sometimes S/s. Otherwise, if you give me the lot number of the panel cells and tell me which cells were positive - a picture would be even better - I can see if I can make sense of the reactions for you

Anna

Yes Anna,I already considered homozygot cells, also I know if I try with another gel panel may success, but this not my question, my question was about why all results were negative with tube however it gives positive with gel?

[Auntie-D]

Yes Anna,I already considered homozygot cells, also I know if I try with another gel panel may success, but this not my question, my question was about why all results were negative with tube however it gives positive with gel?

The simple answer is because gel is a-more sensitive and b-easier to read. My bet is that if you redo your panel in tube and examine the cells microscopically there will be agglutination...

[yiams]

Don't forget there is a sensitivity issue between gel and tube methodologies with gel technique being the more sensitive of the two. How long are you incubating your tube tests? How long are you incubating your gel cards? A 15 min gel incubation that shows agglutination should have an increased incubation time when moving to tube, probably at least 30 minutes with LISS-AHG tube. This is an issue we've been seeing especially with some of our younger techs who have trained with gel while tube reading skills are not as prevalent as they once were. We missed a weak anti-f by going to tube methodology from gel. As one of the Old Farts in our lab, I picked it up when I did the tube work on that patient.