jemarass Posted February 6, 2017 Share Posted February 6, 2017 Hello! We had a patient this morning have a positive antibody screen, so we sent her off for antibody ID which came back negative. I repeated the screen from the original sample and obtained the same results, had the patient redrawn and again same results. We use quotient screen cells, where as our blood center uses ortho. Has anyone come across a case where a patient has an antibody to the reagent? Was this proven in anyway? Patient has an order for 2 units of blood but with no specific antibody available to screen for, I am stumped as to how to call it a compatible crossmatch if we don't know what is causing the positive reactions. Thank you! Link to comment Share on other sites More sharing options...
Vikman Posted February 7, 2017 Share Posted February 7, 2017 6 hours ago, jemarass said: Hello! We had a patient this morning have a positive antibody screen, so we sent her off for antibody ID which came back negative. I repeated the screen from the original sample and obtained the same results, had the patient redrawn and again same results. We use quotient screen cells, where as our blood center uses ortho. Has anyone come across a case where a patient has an antibody to the reagent? Was this proven in anyway? Patient has an order for 2 units of blood but with no specific antibody available to screen for, I am stumped as to how to call it a compatible crossmatch if we don't know what is causing the positive reactions. Thank you! Yes you can for sure have an antibody to a reagent. I have seen it a few times against 0.8% Ortho reagents in GEL. We still primarily test in tube at my reference lab but when I do go to GEL, I tend to dilute out 3% Immucor cells instead of using the Ortho 0.8% cells to avoid any issues. I know in your case Ortho cells were negative but can definitely be directed against quotient cells. Link to comment Share on other sites More sharing options...
exlimey Posted February 7, 2017 Share Posted February 7, 2017 16 hours ago, jemarass said: Hello! We had a patient this morning have a positive antibody screen, so we sent her off for antibody ID which came back negative. I repeated the screen from the original sample and obtained the same results, had the patient redrawn and again same results. We use quotient screen cells, where as our blood center uses ortho. Has anyone come across a case where a patient has an antibody to the reagent? Was this proven in anyway? Patient has an order for 2 units of blood but with no specific antibody available to screen for, I am stumped as to how to call it a compatible crossmatch if we don't know what is causing the positive reactions. Thank you! There are lots of reports of antibodies that appear to need a "co-factor" to react. These are technically not "an antibody to a reagent", as Vikman suggests, but antibodies that only react in the presence of specific chemicals or ingredients in the test system. In this case, it appears that there are differences in formulation of the Quotient and Ortho reagent cells. Quotient has something in their diluent that Ortho does not (and probably the other way around). That "something" facilitates the detection of the ingredient-dependent antibody. As to proving it, I think your test results and that of the other lab already give enough evidence. I have heard of labs that "wash" their screening cells to remove that original diluent and then re-test. You may be able to do that, but bear in mind that if you are doing a gel-test of some sort, the magic ingredient may be in the gel. As to the crossmatch problem, may I presume that the cells from the candidate units are not suspended in Quotient diluent ? They might be compatible because the cell suspensions lack the magic ingredient (but see my caveat above). Yanxia, dragonlady97213 and Malcolm Needs 3 Link to comment Share on other sites More sharing options...
AMcCord Posted February 7, 2017 Share Posted February 7, 2017 (edited) A question to ask would be whether your reference lab simply repeated an antibody screen or if they ran an ID panel? Did they repeat the screen using a screen set from more than one manufacturer? I know that our reference lab does have cells available from more than one manufacturer - this could help determine whether it is a reagent issue or red cell antigen issue. I would suspect that they might have run a panel and that it was also negative. If they did not run a panel, you might request that they do that for your comfort level. You could also send an aliquot of your antibody screening reagent cells to them with a patient sample so that they can see what you are seeing. We have been asked to do that a few times over the years. Are all the reagent cells reactive? If they are and your reference lab got no reactivity I would suspect a reagent issue. Does your patient have an antibody directed against an antibiotic? If that antibiotic is present in the reagent (coating the reagent red cells), then you may be seeing a reaction to the antibiotic, which happens to also be coating the red cells. Red cells that are not coated with that antibiotic (patient cells, donor cells, cells from a different manufacturer) would be non-reactive. If only one cell is positive, I would be inclined to think it might be a patient issue...a 'real' antibody. Another possibility is that your patient has an antibody directed against a low incidence antigen that is on your screening cell but not on the cells used by your reference lab. If that is the case, it may be difficult to identify the culprit. The safest course for crossmatching in that event would be to perform an AHG crossmatch and transfuse crossmatch compatible red cells. Edited February 7, 2017 by AMcCord Another Thought Malcolm Needs, Yanxia and dragonlady97213 3 Link to comment Share on other sites More sharing options...
jemarass Posted February 7, 2017 Author Share Posted February 7, 2017 (edited) A question to ask would be whether your reference lab simply repeated an antibody screen or if they ran an ID panel? Did they repeat the screen using a screen set from more than one manufacturer? I know that our reference lab does have cells available from more than one manufacturer - this could help determine whether it is a reagent issue or red cell antigen issue. I would suspect that they might have run a panel and that it was also negative. If they did not run a panel, you might request that they do that for your comfort level. You could also send an aliquot of your antibody screening reagent cells to them with a patient sample so that they can see what you are seeing. We have been asked to do that a few times over the years. Are all the reagent cells reactive? If they are and your reference lab got no reactivity I would suspect a reagent issue. Does your patient have an antibody directed against an antibiotic? If that antibiotic is present in the reagent (coating the reagent red cells), then you may be seeing a reaction to the antibiotic, which happens to also be coating the red cells. Red cells that are not coated with that antibiotic (patient cells, donor cells, cells from a different manufacturer) would be non-reactive. If only one cell is positive, I would be inclined to think it might be a patient issue...a 'real' antibody. Another possibility is that your patient has an antibody directed against a low incidence antigen that is on your screening cell but not on the cells used by your reference lab. If that is the case, it may be difficult to identify the culprit. The safest course for crossmatching in that event would be to perform an AHG crossmatch and transfuse crossmatch compatible red cells. That's basically what we did! All my cells were reactive which made me think it was something in the reagent causing a reaction (plus the negative results with another manufacturer). As for antibiotics I am not 100% sure, patient came in with a fracture. A third sample was sent out along with an aliquot of our screen cells for the blood center to test with, and I came in this morning to a report with an anti-Bg and unknown IgG reacting antibody though. But thank you for the info! Glad to know it isn't a totally unusual circumstance! Edited February 7, 2017 by jemarass AMcCord 1 Link to comment Share on other sites More sharing options...
TreeMoss Posted February 7, 2017 Share Posted February 7, 2017 We first started thinking about this when we had a patient with positive reactions in all 3 screening cells and all panel cells, but the auto control and two packed cells were negative in gel. How could units be compatible when all screening and panel cells were positive? We then diluted up our Immucor cells to test in gel, and amazingly, there were no reactions. We do report ours as an antibody to the preservative in the Ortho cells. We've seen several times that these patients are on Sulfa drugs, and we wonder if there is a connection there. dragonlady97213, Malcolm Needs, Yanxia and 2 others 5 Link to comment Share on other sites More sharing options...
exlimey Posted February 8, 2017 Share Posted February 8, 2017 13 hours ago, TreeMoss said: We do report ours as an antibody to the preservative in the Ortho cells. For clarification: These are NOT "antibodies to the preservative". If that were the case, they would be neutralized in the presence of the preservative and have absolutely no impact on the serology (except maybe coating RBCs with immune complexes). They are antibodies that react with RBCs only in the presence of a specific co-factor. Malcolm Needs, AMcCord and Yanxia 3 Link to comment Share on other sites More sharing options...
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