labgirl153 Posted July 22, 2006 Share Posted July 22, 2006 Here's a brand-spankin' new ABO discrepancy at my lab...see if you can figure it out before I post the "answer" (yep, needed ref lab assistance for THIS one): 82 yr. old African-American lady from a nursing home comes in to the ER with an upper GI bleed. They pump 900 cc of "old" blood out of her belly, rehydrate her and rule out anything life-threatening before admitting her. ER orders a 2 unit x-match on "hold". She's never been transfused, no bone marrow transplants, no known cancers or monoclonal therapy. She front-types as AB Rh neg, back-types as a group B. Test was repeated using patient cells that were pre-warmed, triple-washed. Same results:anti-A (immucor, monoclonal)...1+anti-B (immucor, monoclonal)...4+anti-D (immucor)....................0Rh control (6% albumin)..........0A1 cells (ortho).......................1-2+B cells (ortho)........................0Antibody screen is negative (ortho gel system). DAT is negative. I ran her against A1 lectin (negative), and tested her plasma against A2 cells (ortho). I got a very weak +/- reaction against the A2 cells. Also, ran her on the Ortho Provue and it duplicated the tube results. Minor x-matches were performed for the heck of it and there seemed to be no polyagglutination (Tn etc.) to account for her "stray" reaction with anti-A monoclonal sera. This was sent on to ARC ref lab for lectin testing and basically to let them play with it. She is perfectly compatible with B Rh neg cells and O Rh neg cells. Patient needed no transfusion and was discharged 2 days later.Ok gang...what could this be? Link to comment Share on other sites More sharing options...
David Saikin Posted July 24, 2006 Share Posted July 24, 2006 ok, I'll bite - Were any blood cultures done? If so, were they positive? I would guess that some bacteria that is producing an acetylating enzyme is transforming some of her "B" cells into "A-like" cells (kind of like a reverse aquired . This bacteria has gotten into her blood stream and is responsible for the ABO effect you are experiencing. Don't keep us waiting too long. Link to comment Share on other sites More sharing options...
Seveets Posted July 24, 2006 Share Posted July 24, 2006 There is a B(A) type that will react with the MHO4 clone of Anti-A reagent. Link to comment Share on other sites More sharing options...
labgirl153 Posted July 25, 2006 Author Share Posted July 25, 2006 Seveets is probably correct...a B(A) pehnotype. ARC also suggested this, and it's the best answer but they could not be conclusive. They suggested DNA testing to get somethng definitive i.e. a true genotype, but it's pricey and our director couldn't justify it. There's a brief write-up in the 15th ed. of the Technical manual (page 298). Doubt if it's been studied enough for statistical data to be generated as to the frequency in the population; however, if anyone has figures on it, or more info on this rare phenotype, let us know. Link to comment Share on other sites More sharing options...
Seveets Posted July 25, 2006 Share Posted July 25, 2006 The tech manual seems to say that those results you got are due to the MHO4 clone used in the anti-A reagent and to verify the B(A) phenotype you test the patient with anti-A that does not have that particular clone. Does each anti-A lot specifies it's clones? Link to comment Share on other sites More sharing options...
labgirl153 Posted July 26, 2006 Author Share Posted July 26, 2006 Yeah, that's a qualification supposedly of the B(A) phenotype...the clone you listed that is (MHO4). This particular patient however, reacted with anti-A of other monoclonal lines as well, so it was a bit confusing to the ref lab ... on one hand, they suggested the B(A) phenotype, on the other, they wanted to discount it based on reactions with other monoclonals. Only DNA testing will yield a definitive answer. Unfortunately, it's a "no-go" situation. Link to comment Share on other sites More sharing options...
javvcr Posted July 26, 2006 Share Posted July 26, 2006 another posibility in an AB patient with a weak expresion of A antigen. some times A expretion could be as weak that the patient could develop and anti A1 or even anti A2. Genotyping is the best way to find out a true answer about it!Maybe and absortion - elution test could help! Link to comment Share on other sites More sharing options...
Yanxia Posted January 29, 2007 Share Posted January 29, 2007 I have met an AX phenotype person, his serum is reacted with A2 cell.TO exclude B(A) phenotype mybe you can use the serum comes from a B type person,too . Link to comment Share on other sites More sharing options...
rcurrie Posted January 31, 2007 Share Posted January 31, 2007 Shily beat me to it. Patient plasma is an excellent source of alternative typing sera.Another alternative might be a reaction with the blue coloring added to the Anti-A, such as is seen with the yellow coloring of the anti-B.BC Link to comment Share on other sites More sharing options...
Yanxia Posted February 1, 2007 Share Posted February 1, 2007 I agree with Rcurri.But the RBCs have been washed before the test,so I think mybe we can exclude this reason . Link to comment Share on other sites More sharing options...
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