Case for discussion:

I received a sample for 35 years old female patient

Multiple delivery all by caesarean section

Results:

BG: A negative

Du : Negative

AC: Negative

DAT: Negative

IAT: positive (3+) all 3 cells

Ab ID: 11 cells All positive (3+)

Then repeat IAT & Ab ID

Incubation at room temperature

All positive (3+)

(Gel technique) (Orthovision)

Column agglutination technology is an excellent technique, but does have a tendency to detect antibodies that react at temperatures well below 37oC, even after fairly prolonged incubation at 37oC.  However, the fact that the blood group, including the "reverse grouping" is clear of atypical agglutination suggests that this may not necessarily be the case for this patient.

Just to be on the safe side though, and if you can, I would either treat the plasma from the sample with rabbit erythrocyte stroma (which will adsorb out most "cold" agglutinins), treat the plasma with 0.01M dithiothreitol (which will denature the J-chains of IgM molecules, meaning that, although they can still sensitise the red cells, they are no longer able to agglutinate the red cells) or, and my personal favourite, is to pre-warm the plasma and red cells to 37oC before mixing, perform the IAT at strictly 37oC in glass tubes, wash with saline warmed to 37oC and use monospecific AHG.  If any, or all, of these techniques lead to negative results, the chances are that the antibody is a clinically insignificant "cold" IgM antibody, such as an auto-anti-HI (given that the patient is group A, and the test cells are all group O)..

Failing the above, send a sample to a red cell reference laboratory.

I hope that helps a little bit.

21 hours ago, Malcolm Needs said:

Just to be on the safe side though, and if you can, I would either treat the plasma from the sample with rabbit erythrocyte stroma (which will adsorb out most "cold" agglutinins), 

I'm curious, where does one find rabbit erythrocyte stroma???  Granted, none of my many years were spent working in a dedicated reference lab but I don't remember ever hearing or reading anything about this technique.  

 

38 minutes ago, John C. Staley said:

I'm curious, where does one find rabbit erythrocyte stroma???  Granted, none of my many years were spent working in a dedicated reference lab but I don't remember ever hearing or reading anything about this technique.  

 

Rabbit Erythrocyte Stroma (RESt) kits are available commercially, but for the life of me, right at this second I CANNOT remember from which company.  I'll get in touch with some of my colleagues who still work (!) and get back to you.

I have been reliably informed that the company is Immucor (Product Code 0057316).  I hope this doesn't break any rules about advertising Cliff Reeves.

Edited January 26Jan 26 by Malcolm Needs
Brain freeze!

That's interesting because I was a long time user of Immucor products.  Thanks for looking that up.  Now I know something I didn't know yesterday. 

Hi Saeeed,

I'm just curious to know where the auto control is. I would expect it to be in well 12 of the IAT panel card.

Also, where are the enzyme panel results?

Also, also, the group card seems to have a different number to the IAT cards - 476258 and 470258?