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It would be really useful if you could tell us the ethnicity and age of the patient, and his medication regime. That having been said, I note that the antibody screen is positive, that his DAT is positive by both anti-IgG and anti-C3d, that the neat plasma contains an apparent anti-E and anti-c, but that the eluate contains an antibody that is, apparently, pan-reactive. Very often in these cases, the apparent antibody specificity in the neat plasma is a mimicking specificity, rather than a true specificity. In such cases, the apparent specificity in the neat plasma can be adsorbed out using red cells that are negative for the antigens of the apparent specificity; in this case R1R1. The true specificity of the antibody could be an anti-Rh17 or anti-Rh18. While I am not saying for a single second that the apparent specificities of anti-E and anti-c are not true specificities, it may be worth your while seeing if they can be adsorbed out using R1R1 red cells. However, as you suspect the presence of other antibodies, this should not be attempted until you have proved otherwise. This you can do, as you suggest, by alloadsorption of the neat plasma using two or three adsorption cell types. In answer to your last question, with regard to adsorption of the eluate, this was certainly a method we used in the Reference Laboratories of the NHSBT in the UK. It was usually used when the patient had a known pan-reactive autoantibody, but was requiring transfusions more frequently than previously, and/or when the expected rise in the haemoglobin concentration was not achieved. On some occasions, we were able to detect a de novo alloantibody in the eluate that we could not detect in either the neat plasma, or the adsorbed plasma, although this was not always the case, as transfusion in and of itself can sometimes stimulate the autoantibody to become more active (see Petz LD, Garratty G. Immune Hemolytic Anemias. 2nd edition, 2004, Churchill-Livingstone). Good luck with sorting it out, but this is a really interesting case. Thank you for posting it and, please, would you mind letting us know how you get on?

Sorry - just saw this reply now. Canadian Blood Services tests all donor units for K. If K negative, the donor end label has K- on it. If K positive, the end label doesn't have any K antigen testing information listed - the K+ status is only embedded in the donor unit phenotype barcode. All donor units are treated the same - so the K+ units are available, as all other units are, but it is easy to select a K- unit for females of childbearing potential and who are on a drug like daratumumab. sandra