Hello, I'm new to BloodBankTalk. We are in the process of switching to gel testing. We recently had a patient that was a previous known Anti-FYA. We did our current tube method and the FYA was still detectable. My tech did a XM with FYA neg unit and thought it was microscopically positive with NHANCE. So I told her to try it in gel 'for fun'. It came out 1+ positive. We then did a gel panel and it showed the FYA but also had other reactivity that did not match any combo of antibodies. I asked the Manager for help and she said to titer out one of the cells that were positive not matching anything. So we did and got a titer of 2. My manager said that using gel, 2-1+ results would be enough to call this antibody a HTLA. I have not seen any literature on this so I'd like to know other techs experiences with gel titers for HTLA. Any comments and experiences would be appreciated.

Thanks

We don't do gel titers for HTLA's. When presented with the scenario you outlined we r/o all of the common clinically significant abs. using 3 heterozygous positives and 4 negatives. We keep two 0.8% panels and one 3% panel for the selected cells. If we can't meet the 3 pos 4 neg with the cells we have our ref lab do just the additional cells for us.

In this case, at our place, your pt would get Fya negative, gel crossmatch compatible units.

I have seen few HTLA and performed gel titer for investigational purpose. I have seen Neat=2+, and then 1+ reaction up to 1:64 well. Which is typical of HTLA. You would see smiliar reaction like tube. (if you have specimen showing 1+ to 2+ in gel, it may not shows up in tube at all.

I also used gel to prove Chido & Rg. In that case you have to make sure that you run albumin control in parallel.

I am very interested in what is HTLA. Is it human T-lymphocyte antigens? And if it is why it will present on red cells? Thanks for any help.

HTLA is "High Titer, Low Avidity" antibody

I am very interested in what is HTLA. Is it human T-lymphocyte antigens? And if it is why it will present on red cells? Thanks for any help.

high titer low avidity

proved by serial titer showing 3-4 reactions at the same strength in neighboring titers

I think it is highly UNlikely that an antibody with a titre of 2 is an HTLA

HTLA antibodies are usually indicated by a titer of 16 or higher and we run them in tube. When testing HTLA in gel we've seen all cells reactive anywhere from 1+ to 4+. If you can find any Knops negative cells, run one or two. Immucor has several donors who are Kn(a-), Yk(a-) and /or McCoy(c-). You may get lucky and one will prove out you Knops sytem antibody.

Unless you have run a validation, I would not go with gel titers.

HTLA antibodies are usually indicated by a titer of 16 or higher and we run them in tube. When testing HTLA in gel we've seen all cells reactive anywhere from 1+ to 4+....

Unless you have run a validation, I would not go with gel titers.

I'm not very good at recognizing HTLAs right of the bat (and esp. because i work at a hospital and not a reference lab), but I would think that "high titer" means a larger number than 2...

and definitely not use gel with HTLA because it'll just react panagglutinable.

HTLA is a term we should avoid using and certainly an antibody should not be called this just because it has a high titer, especially in gel.

There are antibodies that can give a high titer and low avidity and be clinically significant; ie anti-Yta, -Hy, -Doa, etc.

I think the approach to giving crossmatch compatible in gel is a good way to obtain blood for patients when clinically significant antibodies have been ruled out.

BUT, when there are NO negative cells in gel and the autologous control is negative, I would hesitate to call the antibody an HTLA. The sample needs to be sent to a Reference Lab that can determine a specifiity for the antibody.

Marilyn M

Amen on the Yta.... Dont forget there are also several ways to also help determine "HTLAs" (notice the quotes, we also dont like that term) Plasma inhibition and chemical treatments are also some tools. We never use Gel in these titers. Also, by "other reactivity" do you mean 3 out of 11 cells reactive or all 11? USUALLY (we all know that is a dangerous word in BB) these antibodies are on a very high % of cells. Very foggy subject and we often send our samples to a larger Reference Lab that is smarter than us.

I could not agree more with Marilyn Moulds.

Until the specificity is properly determined, calling anything "HTLA" (I don't like the term either!) is very dangerous.