Brenda K Hutson Posted November 2, 2012 Share Posted November 2, 2012 Hi All,Once again, I have been absent for far too long.....sorry, I honestly wish I had more time to logon!Quick question: My predecessor stated in the Policy for A1 Typing that group O cells could be used as the Negative Control. Now, I know the Manufacturer's Insert specifically states "known A2 cells." And though I can't find an explanation, I am thinking that you specifically want A2 (vs. a million other possibilities that would all come up Negative:rolleyes:) because you want to make sure the A1 Lectin is specifically reacting with A1 cells and not just non-specifically, group A cells.But just wondering what your thoughts and/or knowledge is regarding this Negative Control??Thanks,Brenda Hutson, CLS(ASCP)SBB Link to comment Share on other sites More sharing options...
David Saikin Posted November 2, 2012 Share Posted November 2, 2012 I use A2 cells/manufacturer's instructions Link to comment Share on other sites More sharing options...
Brenda K Hutson Posted November 2, 2012 Author Share Posted November 2, 2012 As a seasoned Blood Banker.....like myself, you are probably very strict about following Manufacturer's Instructions. But I guess I just haven't always thought through all of the "why's." So what are your thoughts on why (from a technical standpoint) it should specifically be an A2 cell? I am really just curious at this point. I have every intention of changing my predecessor's Policy to A2....but just curious now (I am very much a WHY type of person).Thanks David!BrendaI use A2 cells/manufacturer's instructions Link to comment Share on other sites More sharing options...
KKidd Posted November 2, 2012 Share Posted November 2, 2012 Brenda, I agree with your thoughts regarding the specificity of the lectin. And then there's always the package insert! Link to comment Share on other sites More sharing options...
R1R2 Posted November 2, 2012 Share Posted November 2, 2012 Hi Brenda,Does the laboratory always have A2 cells? Some do not carry them anymore. Link to comment Share on other sites More sharing options...
David Saikin Posted November 2, 2012 Share Posted November 2, 2012 The lectin is specific for the A1 ag; a subgroup of A should be run to verify that specirficity. What would be the point of running an "O" or a "B" cell? Actually, this lectin has broadspectrum A specificity and is diluted so that agglutiniation only occurs MACROSCOPICALLY with A1 cells. It even works in the buffered gel card . . . A1 cells are 3-4+ and A2 cells are negative. If it reacted with A2 cells then you could not type anyone as an A1 with any confidence, hence the A subgroup cell should be negative and is therefore your negative control. This seems like Aquinan Logic but it actually does make sense.- - - Updated - - -Hi Brenda,Does the laboratory always have A2 cells? Some do not carry them anymore.then they should not be using A1 lectin. Link to comment Share on other sites More sharing options...
R1R2 Posted November 4, 2012 Share Posted November 4, 2012 The lectin is specific for the A1 ag; a subgroup of A should be run to verify that specirficity. What would be the point of running an "O" or a "B" cell? Actually, this lectin has broadspectrum A specificity and is diluted so that agglutiniation only occurs MACROSCOPICALLY with A1 cells. It even works in the buffered gel card . . . A1 cells are 3-4+ and A2 cells are negative. If it reacted with A2 cells then you could not type anyone as an A1 with any confidence, hence the A subgroup cell should be negative and is therefore your negative control. This seems like Aquinan Logic but it actually does make sense.- - - Updated - - -then they should not be using A1 lectin.I agree David, but I have seen this. It didn't make sense to me either. Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 5, 2012 Share Posted November 5, 2012 Hi Brenda,I agree that known A2 red cells should be run as the negative control.Dolichos biflorus lectin is NOT specific for the A1 antigen, until it has been diluted to a degree that takes away the broad anti-A specificity, and even then it retains the ability to agglutinate Tn+ and Cad+ ("Super Sid") red cells.The key to the use of a negative control is that the cells used should provide the "strongest" expression of an antigen with which the antibody is not expected to react. In the case of polyclonal anti-D, for example, the most common contaminent was a weak anti-C. When these polyclonal reagents were used, therefore, the "correct" negative control cell used was an r'r' (although, in practice, an r'r cell was often used, as very few laboratories indeed had access to r'r' red cells).In these days of much more specific monoclonal antibodies, we have, perhaps, become blase about such things (although it should be remembered that certain monoclonal anti-D reagents have an element of an "anti-I-like" specificity when used straight from the fridge). We should not be. Remember that a patient died because a monoclonal anti-B reacted strongly enough with an individual's red cells with the acquired-B (clone ES4, if my memory serves me - but don't take that as Gospel) and AB blood was transfused.In the case of Dol. b., of course, we are NOT using a monoclonal reagent, and so we should "revert" to using the correct (A2) red cells for a negative control, otherwise we are controlling absolutely nothing. Link to comment Share on other sites More sharing options...
Rh-fan Posted November 5, 2012 Share Posted November 5, 2012 In general your controles should "look like" the cells you are testing. SO if you use anti A1 lectin to discriminate betweeen A1 and A2, you should use a A1 (as positive) and A2 as negative.This rule can be applied almost always, unregarded what the manual says. Use you common sens and brain.Peter Link to comment Share on other sites More sharing options...
Dr. Pepper Posted November 5, 2012 Share Posted November 5, 2012 I agree on using A2 cells as the other posters have stated. We buy reagent A2 cells to QC the lectin and to help in identifying anti-A1. Link to comment Share on other sites More sharing options...
Mabel Adams Posted November 6, 2012 Share Posted November 6, 2012 At a smaller hospital that might keep anti-A1 lectin but have a hard time justifying the cost of A2 reagent cells I want to throw out this logic and let you tear it to shreds: We run positive controls to allow us to detect a reagent or testing failure causing a false negative result; we run negative controls to allow us to detect when a reagent or testing failure is giving us a false positive result, right? As long as the test of the patient's cells is negative, you can't have a false positive. What you can't truly trust if you are running O cells for a negative control is the positive results you get.In terms of logic, not regulations, could a place use the lectin with only a positive control and trust the results only if the patient tested negative with the reagent? That is, could they call patients A2 but never call them A1 and be scientifically correct? If the sample tested positive with the lectin they would either have to send the test out for further workup or solve the discrepancy by some other means.It seems that when I finished school in the dark ages no one seemed to expect that controls (at least not negative ones) were run for A1 lectin. Years later as this got added to package inserts they didn't always say what negative cells should be run. I'm married to an A2 and gave birth to another one so I used to know where I could get some A2 cells when I needed them--but that was before making your own reagents was so impossible. All right, have at it, guys. Link to comment Share on other sites More sharing options...
RebeccaS Posted November 6, 2012 Share Posted November 6, 2012 Rebecca with Hemo bioscience here. Definitely looks like several of you are on the right track with this one. Thought it might be good to offer a manufacturers perspective to this:During manufacture a very potent preparation of dolichos will detect A2 cells. The ability to detect these cells is usually diluted out by the manufacturer. Therefore A2 cells should always be used as a negative control.Have A Great Day! Link to comment Share on other sites More sharing options...
Dansket Posted November 6, 2012 Share Posted November 6, 2012 At a smaller hospital that might keep anti-A1 lectin but have a hard time justifying the cost of A2 reagent cells I want to throw out this logic and let you tear it to shreds: We run positive controls to allow us to detect a reagent or testing failure causing a false negative result; we run negative controls to allow us to detect when a reagent or testing failure is giving us a false positive result, right? As long as the test of the patient's cells is negative, you can't have a false positive. What you can't truly trust if you are running O cells for a negative control is the positive results you get.In terms of logic, not regulations, could a place use the lectin with only a positive control and trust the results only if the patient tested negative with the reagent? That is, could they call patients A2 but never call them A1 and be scientifically correct? If the sample tested positive with the lectin they would either have to send the test out for further workup or solve the discrepancy by some other means. ...In the case of Anti-A1 lectin reagent, the purpose of the controls are to demonstrate that the reagent can correctly distinquish between A1 and A2 cells..In a facility where appropriate controls cannot be tested and the test is being done to resolve an ABO discrepancy in a patient who may require blood transfsion, one could make a case for that situation to routinely select group O red cells for transfusion. Then send the specimen to a reference lab. Link to comment Share on other sites More sharing options...
aafrin Posted November 7, 2012 Share Posted November 7, 2012 We are a small blood bank (hospital attached). We make pooled donor cells for A1, A2, B, A1B, and O Cells daily for use in QC of our antisera and A1 Lectin and also for reverse typing. Is that OK or are we supposed to buy manufactured reagent red cells only. Usually we use A cells not agglutinated by A1 lectin even at 4 degree centigrade as A2 cells. Since our stock of blood is usually low, we sometimes do not have any A2 donor cells and hence we are currently thinking of using pooled patient cells from our health check packages. Will that be OK with FDA? or is there another solution. Our facility does not want to spend on reagent red cells -!! Link to comment Share on other sites More sharing options...
cbaldwin Posted November 7, 2012 Share Posted November 7, 2012 Just curious--what is used for a negative control for anti-A? Link to comment Share on other sites More sharing options...
Dr. Pepper Posted November 7, 2012 Share Posted November 7, 2012 Although I think donor cells would work fine for backtype cells, AABB Standards specifies "reagent red cells" for typings. I guess it's how one defines "reagent". AABB doesn't specify that "reagents" be commercially prepared. Anyone have the FDA regulatory slant on that? And I do have a problem using a reagent (anti-A1) to find the A1 and A2 cells to QC that same reagent. Link to comment Share on other sites More sharing options...
Dansket Posted November 7, 2012 Share Posted November 7, 2012 Just curious--what is used for a negative control for anti-A?In our facility, ABO typing is done on ProVue. A/B/D Reverse Grouping gel cards are tested against group A1 red cells (positive control) and group B red cells (negative control) using commercially available simulated whole blood controls. Link to comment Share on other sites More sharing options...
galvania Posted November 7, 2012 Share Posted November 7, 2012 Just want to say - a bit late - that I think Malcolm's logic is spot on (as usual) as to why it is neccessary to use an A2 as a negative control rather than something else. Link to comment Share on other sites More sharing options...
cbaldwin Posted November 7, 2012 Share Posted November 7, 2012 Just curious--what is used for a negative control for anti-A?OOPS!!!!! I MEANT, what is used for a negative control for anti-H!!!!!! Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 8, 2012 Share Posted November 8, 2012 OOPS!!!!! I MEANT, what is used for a negative control for anti-H!!!!!!Well in my lab we use Oh red cells, but I know these are not available to most people. Link to comment Share on other sites More sharing options...
cbaldwin Posted November 8, 2012 Share Posted November 8, 2012 Well in my lab we use Oh red cells, but I know these are not available to most people.Hi Malcolm! Are those reagent Oh cells or patient? Thank you! CLB Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 8, 2012 Share Posted November 8, 2012 Well, they can be either.Once we've found either a donor or a patient who is Oh, we freeze them down at -80oC, and then reconstitute as required. We try to get a range of Oh cells that cover all of the other antigens, although this is not easy.......and before anyone else says it, I KNOW I AM REALLY, REALLY LUCKY TO HAVE THIS FACILITY!!!!!!!!!!!!!!!! Link to comment Share on other sites More sharing options...
Mabel Adams Posted November 9, 2012 Share Posted November 9, 2012 If I recall, anti-H can be used to help identify A intermediates. Should no one use anti-H lectin for this unless they have Oh cells? Not that knowing someone is A int is ever clinically significant... Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 9, 2012 Share Posted November 9, 2012 If I recall, anti-H can be used to help identify A intermediates. Should no one use anti-H lectin for this unless they have Oh cells? Not that knowing someone is A int is ever clinically significant...I think that you answered your own question really Mabel, with your last sentence. In other words, does it matter, and in any case, in these days of really potent and specific monoclonal ABO reagents, are we likely to detect them as often as before? Link to comment Share on other sites More sharing options...
Mabel Adams Posted November 10, 2012 Share Posted November 10, 2012 I just have a personal bias since I am A intermediate as are all of my siblings. Link to comment Share on other sites More sharing options...
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