Gel and anti-e

[jschlosser]

We had a patient come in for 3 units of PC. She had recently(last month) received one unit of PC and 3 units of FFP at another facility. We had a positive screen so we did Ortho Panel A and B. The reactions were confusing but it looked like a Jka. Lot of inconsistent rections like a Jka homozygous cell not reacting and another homozygous reacting etc. We know Jka can do this but we weren't comfortable with just calling the Jka so we referred it out. They confirmed the Jka and also found an anti-E. We had ruled E out with a homozygous and a heterozygous cell so we were suprised. They had used an Immunocor Panel and an Ortho panel and PEG to come to the anti-E. If the patient hadn't had the Jka, she could have easily received E positive blood. How can we avoid this in the future?

I do have another question out of all of this. We're a small lab and the extent of our antibody ID is Otho Panels A and B.

When Jka has such inconsistant reactions in regards to hetero and homozygous cells we aren't comfortable calling it Jka. Wouls you confirm it with other methods or would you go with the panel results only. Thanks Much

[jschlosser]

Sorry. This should be titled Gel and anti-E.

[Malcolm Needs ☆]

Well, the first thing that I would say is that, like all (or nearly all) Rh antibodies, anti-E is best detected by the use of enzyme-treated red cells and, to a certain extent, the use of PEG mimics this. Do you use PEG in your Laboratory, or straight IAT. If it is the latter, you may miss an anti-E.

That having been said, an "enzyme-only" anti-E may often be "naturally-occurring" and is highly unlikely to be clinically significant (although there are very isolated reports in the literature of such an antibody causing a reaction - but they are few and far between). This is why the "enzyme" screen was dropped some years ago now.

On the other hand, any antibody that remotely looks like an anti-Jka should be treated as an anti-Jka, because this specificity is so labile, both in vitro and in vivo, and it is always worthwhile playing it safe and giving Jk(a-) under such circumstances. Anti-Jka causes some really serious reactions, following anamnestic responses, as can be seen in many audits of reactions throughout the world.

[jschlosser]

We don't have PEG but use Antibody Enhancement from Ortho. Thinking of losing this and getting PEG.Thanks for your help.

[tbostock]

Malcolm, do you have any references about the very weak "enzyme-only" anti E phenomenon? We are currently implementing the Tango analyzer and two samples that had anti-E (VERY weak reactions) in gel are coming up negative on the Tango. I had heard that gel can pick up this type of anti-E and they are usually clinically insignificant, but I can't seem to find a reference for it, so that I can explain why the Tango did not pick them up.

Other than the old standby: "not every method detects every antibody" defense.

[Malcolm Needs ☆]

Malcolm, do you have any references about the very weak "enzyme-only" anti E phenomenon? We are currently implementing the Tango analyzer and two samples that had anti-E (VERY weak reactions) in gel are coming up negative on the Tango. I had heard that gel can pick up this type of anti-E and they are usually clinically insignificant, but I can't seem to find a reference for it, so that I can explain why the Tango did not pick them up.

Other than the old standby: "not every method detects every antibody" defense.

Give me a couple of days Terri. I'll find them.

[MAGNUM]

The PEG is great, I use it for all my ID's, but you cannot "lose" the antibody enhancement since PEG does destroy certain antibodies invitro such as your Duffy's, so you need your regular enhancement also.

[Malcolm Needs ☆]

I don't want to be picky, but I think it is the antigens that PEG affects, rather than the antibodies - otherwise all antibodies would be affected whatever the specificity.

It's a bit like papain denaturing the M, N, S, s, Fya and Fyb antigens, rather than denaturing the antibodies.

[Malcolm Needs ☆]

Give me a couple of days Terri. I'll find them./QUOTE]

So much for a couple of days Terri. If I was perfectly honest, I must admit that I forgot this, but here they are now.

Mollison PL, Engelfriet CP, Contreras M. Blood Transfusion in Clinical Medicine, 10th edition. Oxford: Blackwell Science, 1997.

Heisto H. An anti-E antibody reacting strongly with enzyme-treated cells, but showing no signs of agglutination or absorption with untreated cells. Acta Path Microbiol Scand 1955; 26: 381-384.

Vogt E, Krystad E, Heisto H, Myhre K. A second example of of a strong anti-E reacting in vitro almost exclusively with enzyme treated E positive cells. Vox Sang 1958; 3: 118-123.

Dybkjear E. Anti-E antibodies disclosed in the period 1960-66. Vox Sang 1967; 13: 446-448.

Harrison J. The 'naturally occuring' anti-E. Vox Sang 1970; 19: 123-131.

These publications are all cited by Daniels G. Human Blood Groups, 2nd edition. Oxford: Blackwell Science, 2002.

Once again, sorry for the delay.

:whew::whew:

[tbostock]

So much for a couple of days Terri. If I was perfectly honest, I must admit that I forgot this, but here they are now.

Once again, sorry for the delay.

:whew::whew:

That's OK, Malcolm...as usual, you are worth the wait! Thank you so much for your help.