Discrepant reverse grouping due to anti M

[dcubed]

When a reverse group does not agree with the forward type due to a cold reactive antibody, such as anti M, is it required to find A1 and B cells that lack the antigen and repeat the reverse grouping with those cells?

[Auntie-D]

Usually corrects itself if you do the group warm (not the antibody screen of course).

[Desoki]

I think it is better to neglect reverse.

[rravkin@aol.com]

We perform a tube panel with LISS enhancement and read at all phases in order to rule in the Anti M specificity. If you did use A1 and B cells lacking the M antigen this may be concidered a somewhat indirect ID of the specificity because one can not satisfy the statistical knoll hypothesis with this method of ID.

[Malcolm Needs ☆]

We would always use M- red cells to re-do the reverse group; it may also be anti-A1 (and we don't routinely run A2 red cells in our reverse group). One has to remember though, that I work at a Reference Laboratory and can get my hands on absolutely masses of different red cell types!

[Eagle Eye]

With the gel we see ABO discrepancy and negative antibody screen. At this point if we know that patient has H/O anti-M, we type new lot of reverse cells(0.8% & 3%) for M and comment that reverse cells tested M+. If we see the same with new patient/first time patient, we do tube method screen and additional testing to confirm anti-M Vs non specific cold at least once.

[khalidm3]

You should not neglect, find M-, reverse cells and test.

[Desoki]

You should not neglect, find M-, reverse cells and test.

You are right mohammad khaled sorry, we should not neglect reverse grouping

[Rh-fan]

In the absence of M- A or B cells you can treat them with an enzyme (ficine, papaine or bromelain), and in case of anti Le or anti P1 you can use LE or P1 substance to neutralise the antibodies

[Malcolm Needs ☆]

In the absence of M- A or B cells you can treat them with an enzyme (ficine, papaine or bromelain), and in case of anti Le or anti P1 you can use LE or P1 substance to neutralise the antibodies

Excellent points Peter.

[dcubed]

Thanks to all for the input. We have had 3 such patients in the past couple of weeks. Maybe the backtype cells we are using have a particularly strong M expression.

[Mabel Adams]

In the US reverse cells are pooled so essentially always are M positive due to the antigen frequency in the donor population. I'm sure they can be stronger sometimes than others.

What is a good solution for small labs that don't have enzyme, keep anti-M antisera or have known M neg A cells on hand? About all I know of is to warm the reverse type but it always bugs me because ABO antibodies are also cold-reactive so it seems like it may defeat the purpose.

I did have the good sense to marry and give birth to M neg A pos people but they are A2s so, although I have used their samples in these cases, it is not quite the same as if they were A1 (and not exactly licensed reagents). Of course if the patient is A1 they shouldn't be able to make anti-A1 so it can be ruled out that way sometimes.

[Eagle Eye]

I believe keeping anti-M on hand may be cheaper as you will be doing this once every four week. You may not get a patient who will have ABO discrepancy due to anti-M. Our population we do not notice this until we have a A, B or AB patient who has anti-M. AT that point we type our A cell & B cell for M and then make a note in our communication log book.

I do not know if you will have a luck in getting M- A1 cells every month and let's say you keep the reagent on hand and you do not get a patient with anti-M, your A1 cell will expire in 4 weeks>>>>

[Mabel Adams]

It sounds like you sometimes find M negative A1 reverse typing cells. Is that correct?