LIMPER55 Posted November 24, 2015 Share Posted November 24, 2015 We sent a Warm Auto Antibody specimen to our reference lab. The patient had previously been transfused 9/23/15. The work up came back as no underlying clinically significant antibodies.My concern: The reference tech antigen type the specimen for E and little c...The direct coombs (IGG) was positive. The explanation I got was that the antigen typing was stronger than the direct coombs.Is this valid ? Link to comment Share on other sites More sharing options...
SMW Posted November 24, 2015 Share Posted November 24, 2015 Most anti-E and anti-c reagents are not intended to be tested at the antiglobulin phase. If the control in use as perscribed by the package insert (which is generally not at the antiglobulin phase) was negative, the test results are valid. Malcolm Needs 1 Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 24, 2015 Share Posted November 24, 2015 The direct coombs (IGG) was positive. The explanation I got was that the antigen typing was stronger than the direct coombs. Most anti-E and anti-c reagents are not intended to be tested at the antiglobulin phase. If the control in use as perscribed by the package insert (which is generally not at the antiglobulin phase) was negative, the test results are valid. PLEASE LIMPER55, do not call it a direct coombs (or Coombs) test; it is the direct antiglobulin test! Although both the indirect and direct antiglobulin test was described by Coombs RA, Mourant AE and Race RR (so it wasn't just Coombs), the principle of the test was described by Moreschi (a microbiologist) some 40 years before, and all three (Coombs, Mourant and Race) used to HATE the tests being called the indirect Coombs test and the direct Coombs test. Sorry, but it is also one of my pet hates!!!!! SMW, I completely agree with you. Most Reference Laboratories (and, I think, most hospitals) now use monoclonal antibodies directed against the D, C, E, c and e antigens, and, as you so correctly state, they are not designed to be taken through to the antiglobulin phase, but they ARE designed to give negative results with DAT positive red cells that lack the cognate antigen, as long as the control with the patient's red cells is negative. If the patient's red cells are being sensitised by a "cold" autoantibody, you may get a false positive, but then, the auto-control (i.e. the patient's red cells in the antibody diluent, but lacking the actual antibody - if you see what I mean) would also be positive, and so the test would be invalid. amym1586 1 Link to comment Share on other sites More sharing options...
David Saikin Posted November 24, 2015 Share Posted November 24, 2015 I find it hard to believe that a reference lab would be using Rh typing sera that required antiglobulin testing. (maybe using their own home brew?) Don't take this personal Malcolm but I find that occasionally reference facility staff will talk "down" to hospital technical staff. I'll bet that is what transpired to Limper. Malcolm Needs and LIMPER55 2 Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 24, 2015 Share Posted November 24, 2015 I agree on both counts David. Link to comment Share on other sites More sharing options...
goodchild Posted November 24, 2015 Share Posted November 24, 2015 What about the recent transfusion? LIMPER55 1 Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 25, 2015 Share Posted November 25, 2015 As long as no mixed-field reactions were detected in any of the tests, the results are valid. David Saikin 1 Link to comment Share on other sites More sharing options...
Dr. Pepper Posted November 25, 2015 Share Posted November 25, 2015 One would also think that the reference lab would have the reagents necessary to remove the IgG if need be. Malcolm Needs 1 Link to comment Share on other sites More sharing options...
Malcolm Needs ☆ Posted November 25, 2015 Share Posted November 25, 2015 Excellent point Phil, which, having worked in such a laboratory for almost all of my professional life, I had completely forgotten!!!!!!!!!!!!!!! Dr. Pepper 1 Link to comment Share on other sites More sharing options...
Dr. Pepper Posted November 25, 2015 Share Posted November 25, 2015 Such is the price for a life of dissolution and debauchery - but it HAS been fun. AMcCord and Malcolm Needs 2 Link to comment Share on other sites More sharing options...
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