[ag phenotyping in chronic transfusion recipients]

I agree with David and Shily.

David for the 3 months for serological typing, and Shily for the suggestion that you use a genetic approach.

Certainly, these days we use a genetic approach in the NHSBT if we want to know the patient's actual type, and this can be done immediately after a transfusion.

We are a small facilityand don't have gene typing facility around also. Can anybody please share the SOP for retic typing?

Thanks in anticipation.

[Mixed fields]

we do grade mf and I agree with rcurrie that grades are extremely helpful in picking up weaker groups.

One more thing, has anybody noticed these mf reactions on "slide"? These appear 'beautiful' and you can actually see them getting stronger from "within-out" and differentiate them easily from weaker reactions say 1+ or 1+(w), especially for techs who are not very interested somehow in picking these reactions!

[antibody screening in Indian population using Caucasian cell panel?]

Hi There from a new member. I am the Technical Director of an Australian Immunohaematology manufacturer but I spend most of my time in Asia. I often see the picture you describe. As an example, in the Philippines, some Hospitals report that around 30% of antibodies found in crossmatches are not detectable on caucasian screening cells and do not react with caucasian ID panels. They are not auto or so called false negatives. They are really alloantibodies that have specificity for antigens that are rare in caucasian populations but are relatively common in Asian populations. These antibodies in this population are likely to be vMNS (the new nomenclature for the 11 antigens formerly known as Miltenberger or Mi and includes MUT, Mur and Mia and others). Some will also be Diego a that is not commonly found on screening panels.

A literature search shows that these antigens and antibodies are not characterised in India itself but published studies (Prathiba, 2002) in Malaysian Indian populations show that 3% of that population are vMNS or Mia positive. Malaysian Chinese are 4.9% and Malay 2.8%. vMNS antibodies have also been found in the Sri Lankan population whose dominant Sinhalese population are ethnically distinct from but have similar phenotypes to the Indian sub-continental populations.

As an example a very large study in 2003 by Lee et al showed that the the alloantibody incidence in Hong Kong antenatal patients was 0.27% and 57.6% of these were classed as Anti-Mi. The antigen incidence of Mia in HK was shown to be 6.3 by Poole et al in 1991. This antigen incidence is right in the ball park to generate a very significant antibody incidence. Lots of antigen negative blood recipients and mothers but a significant antigen positive number of blood donors and babies.

I would point out a few things about these studies.

1. They were state of the art at the time but the knowlege about vMNS has changed in the last few years. The antibody screening was done with natural cells that were shown to be Mi positive by the only monoclonal antibody available at the time. In reality they are uncharacterised and are likely to be what we would now call Mi III. In this case, they may miss some vMNS antibodies, so the real incidence is likely to actually be higher.

2. vMNS antibodies seem to behave like other antibodies of the MNS system in that there are so called "naturally occuring" forms that are probably better called "non-red cell immune" and these are IgM and cold reacting and likely to be clinically irrelevant. Others are alloimmune in nnature, IgG and clearly very capable of causing severe transfusion reactions and HDFN. Some as yet unpublished work has shown that in some populations that up to 40% of vMNS antibodies are IgM and likely of little clinical harm. The other 60% we should be very worried about.

For this reason, I hold the opinion that testing laboratories in Asian countries have to continue to IAT crossmatch to detect these antibodies. I can back this up with many anecdotal cases where I have seen Asian laboratories adopt western style group and screen blood release protocols only to find a very significant number of transfusion reaction in patients who are antibody screen negative (using imported western panels) and who are transfused ABO compatible blood. If you have a look at Taiwan as an example. They have published a large body of work and are very well aware of the high incidence of vMNS antibodies and the clinical relevance of them in their population. They therefore tend to screen with an imported panel BUT also add a locally made 3 cell panel that would be unusable in a western country but does have Mia and Dia on it. So they routinely do a 6 cell antibody screen to try to cover all the antibodies in their population. They also tend to use the Polybrene technique that I personally do not like but they feel has high sensitiivity to vMNS antibodies.

To date, India has not been well studied and certainly nothing substantial has been published. I think that while the Indian phgenotypes are significantly different from other more Eastern asian populations, there is sufficient evidence to beleive that the Indian population will have a very significant incidence of very clinically relevant vMNS antibodies that will not be detected on normal imported panels.

So transfusionpgi, as a final note, my group has very recently come up with a solution to this problem. We have and are running a number of studies in Asian countries to update or define the incidence of red cell antigens and the incidence and specificity of alloantibodies. PM me if you would like to know more or are interested in participating in a study I am planning.

Dear TimOz,

Very thanks for sharing the useful information. Your description was really enlightening!

We have decided to implement the imported panel with 'retrospect' use of "in-house" panel, in case something comes positive while screen is non-commital.

We would love to be a part of your study group. Kindly provide your mail I.D.

Mine is bloodbank.abmh@adityabirla.com

[antibody screening in Indian population using Caucasian cell panel?]

We electronic issue - if screen neg and no previous history of antibodies, also require 2 x groups on LIMS.

I would have thought that until you resolve your 20% incompatibility problem, you would need to carry on with performing this.

How reliable is the testing (ABO, screening, etc) performed on your donor units...do you find many incorrectly labelled ones, or does the blood service have good donor unit tracking, from the point of collection to final bag labelling ?

It's very interesting to learn of the challenges facing blood bank folk in other countries.

Electronic issue is still a 'far cry' for us. I am sure your LIMS must be validated nicely! Are you following some guidelines?

We plan to continue it (AHG Xm) till we either have our cell panel or population profile done (for ags).

Now, there again is a 'news' for you! Blood supply here doesn't have segregation as blood suppliers and transfusion centres/ hospitals (more of it some other time), but ...Yes, labeling and other processes are well validated and we don't find these kind of errors anymore (yes, we did have them initially though)

[antibody screening in Indian population using Caucasian cell panel?]

Dear Transfusion gpi

I see you are doing a gel crossmatch. I presume the gel is DiaMed gel. Am I correct in thinking that you are also using DiaMed screening cells to do the antibody screen? Or are you just sending the sample off for an identification panel if the crossmatch is positive? Either way, you should really get in touch with DiaMed India in Gurgaon (always assuming you are using diamed gel). I can promise you they have an EXCELLENT team of specialists who will be able to advise you.

Dear Galvania!

You are bang on target! We indeed use Diamed gel cards and send anything which cannot be resolved at our end to Diamed people. How do you know that they have their headquarter in Gurgaon?

Anyway, since Diamed is one of the stake holder in the entire seen, their view is bound to be biased and in fact is biased, as they do not even recommend Aisan Diacell panel (which I presume is short in supply and thus they don't mind dispatching whatever is available).

You seem to be related to Diamed in someway, is it?

[ag phenotyping in chronic transfusion recipients]

what is the right time for antigen phenotyping after a blood transfusion, especially in chronically transfused recipients, like those with tx dependent thalassemia, CRF on hemodialysis, etc.

(We know that type of agglutination pattern in tube or gel will give a clue to ****- or heterogenity of rbc population, eg. mixed field, weaker agg, etc. Still what is the "IDEAL' time interval after last tx?)

[Tube Groups- decline of ?]

YES, YOU SHOULD MOST DEFINITELY BE WORRIED.

There is an old saying that "you should learn to walk before you learn to run" and another that goes along the lines of (and I paraphrase, because I cannot remember the exact phrase) "Those who don't learn from history are destined to re-live it".

There are very many occasions when tube techniques are still superior to column agglutination technology, liquid phase microtitre plate technology and solid phase microtitre plate technology, not least in cases of a "cold" auto-antibody of wide thermal range.

One of the main reasons that I insist that all of my staff are adept at and all of my students are aware of tube grouping and tube antiglobulin techniques is so that they have a basic (and I use the term in the meaning of fundamental) knowledge of how human (patient) IgM molecules and IgG molecules react and, most important of all, what are the fundamentals of the direct and indirect antiglobulin techniques. Without such knowledge, they are learning by rote, and will perform as a person who has learnt by rote.

I REPEAT, YES, YOU SHOULD MOST DEFINITELY BE WORRIED.

Dear Malcom,

I fully agree with you and just to complete your quote - "Those who don't learn from history are destined to re-live it"

was originally written as ""Those who don't learn from history are liable/ prone to repeat its mistakes".

[How did you find BBT?]

I was searching on google for some answers regarding one of clinico-immunohematology problems that I faced one day. That's how I reached this site, looked at the contents and topics posted - got hooked to it from then on.

[Positive DAT that goes away?]

We had a DAT last night that was positive ( mixed field really) at AHG but after the 5 min room temp incubation ( we use poly) to enhance complement, it was completely negative. I think that patient may have some rouleaux or some non-specific protein that is causing stickiness but does not really indicate a pos DAT. Anyone else have any experience with this?

Thanks.

Hi Lara!

Had I been in your place, I would've recorded the finding and given the test result as negative, keeping in mind that patient didn't have anything clinically suggestive. Some studies quote positive DAT to the tune of 10% of hospitalized patients without any significance.

Recording the finding (i.e. + and then negative over 5 min) will help you correlate similar findings in future.

Anyhow, what was the result with anti-IgG (AHG), if it was done at all?

Also, do you use only tube technique only or some other also? Gel can provide better understanding with mf type of reactions.

[positive HCV test!]

Thanks for all ideas. I have checked that sample with NAT, and it was positive.

You see, engeekay was right, better to discard one unit than be in doubt. We too discard any sample coming positive by any (be it rapid, ELISA, etc.) technique. Also, which ELISA kit are you using? This type of result can come due to delay in tesing, sample error, sample storage conditions, technical error, using low sensitivy ELISA kits, etc. There are many good rapid tests available in the market which perform better than some ELISAs.

Amongst all Ortho ELISA seems to be better than the most in the lot.

Thanks for sharing the info.

[antibody screening in Indian population using Caucasian cell panel?]

Thanks for the reply.

You are correct. We still don't have antigen profile available for our population. Big studies are underway for the same. This will help companies develop indigenous cell panel. Also, study (done at one big centre in India, and not by us) did find one anti-Mi(a) in the patient population.

We are beginning this exercise with our population. Till now we were doing Grouping and crossmatching without ab screen for our patients.

[antibody screening in Indian population using Caucasian cell panel?]

You are saying that 20% antibodies are not being detected on your screen/ panel but are being picked up on crossmatch ?

This is extremely high. Have you eventually identified these antibodies- and if so what were they (you mentioned they were clinically significant).

In the UK we have a fairly diverse population, and have used the National Blood Service manufactured screens and panels (which I presume are mainly from caucasian donors)- had no noticable problems with transfusions in mixed recipient populations.

Thanks for the reply.

We are still a new set up and what I quoted was from 2 good centres in India (both are teaching institute with transfusion courses running there). Author of the study only said, "missed abs were clinically significant", without mentioning the specificity.

We are planning to start the ab screening for all our IP patients and this was recently OKeyed by our Hospital Transfusion Committee. Thus this query of mine.

Do you routinely crossmatch (AHG) patient samples negative on ab screen? Or is it just IS/ Electronic Xm?

[antibody screening in Indian population using Caucasian cell panel?]

Dear Colleagues,

I would like to get your comments on the topic.

We are a tertiary care health set up in Western India and want to start ab screening for all patients who might require blood transfusion. Just to appraise you of situation in our part of the world regarding Blood Banking:

1. Antigen profile of the populatin is not available yet. Whatever studies have been done are not true representation of the entire population.

2. Only fewcentres are aware of (still cannot say well versed) the immunohematology techniques applicable and still few practice them. This to the extent, that even tube technique for cross matching (with or without AHG) is not know to many blood banks.

We group & type our patients for ABO and Rh(D) and perform gel crossmatch. Any ab found is resolved 'retrospectively' .

Now, coming to the query - Studies done in India (2-3) have shown that sensitivity of (picking ab by) currently available cell panel is only 80% i.e. no ab on cell panel still crossmatch incompatible. These were for clinically significant abs.

Q1) So what is the solution? How do we go about it?

Q2) what are the advantages of ab screening in pre-transfusion sample in this scenario?

Thank you