Whitney Poplin

Or maybe I should say, if there was bacterial contamination sufficient enough to alter the M antigen, would this not also make the cell polyagglutinable?

One patient example of anti-M is reacting strong 3+ with all of the other single-dose cells on the panel. This cell #6 is also a single-dose cell. There was no evidence of contamination; i.e. no hemolysis or discoloration of the reagent. If there was bacterial contamination and therefore a bacterial deacetylase that possibly removed NeuAc (sialic acid) off of GPA, wouldn't the cell also become polyagglutinable? I can't remember if that process actually alters the M antigen. This cell was not reacting at immediate spin with the patient's sample, either, as it was with the other reagent cells. I converted cell 6 along with 2 other single-dose cells to 3% and tested all 3 against commercial anti-M, and they all reacted equally at 2+. I would have to check the package insert to see if M1+ cells react with the commercial anti-M; however if I remember right, M1+ cells are almost if not always M+ as well. Is there was a situation where the M antigen would be altered or have a decreased expression that would react with commercial anti-M but not patient anti-M? Anyone?

Yeah ..... I obviously didn't think that one through. Probably hadn't had enough caffeine yet.

If the patient's antibody screen is currently negative, then that automatically rules out C and K even though they weren't ruled out 5 years ago. Therefore it is not indicated to give C and K negative units now. Was the patient transfused at that time (5 years ago?)

Hi Karrieb61, Are you referencing performing eluates for pos-transfusion investigation or for mother/baby ABO incompatibility? My view is that the DAT is a crappy test . . . er, ahem . . . it is not a sensitive test. One can easily get a negative DAT and end up getting a specificity out of the eluate, since the eluate concentrates the antibody. At our facility we currently look at all DAT's microscopically, which is a bit of carryover from previous management. We do eluates on micro + DAT's if the patient has been transfused in the last 2 weeks. If I remember right, we have gotten specificities out of eluates performed on samples with micro + DAT's (at least if I remember right. Help me out here, Mabel.) For babies, we still report the DAT as pos (even if just micro+) and that is where the workup stops. We don't do further investigation to prove it is maternal anti-A or anti-B causing the positive DAT. However I suppose we would investigate further if the physician requests us to do so.

oops sorry - computer issues

Ortho Clinical Diagnostics 0.8% Panel A, lot # VRA215 exp 2/17/15, cell #6: We have had 2 examples of anti-M that react with all double- and single-dose cells except cell #6. Cell 6 is M+N+, and it DOES react with commercial anti-M. One of these examples was reacting at a strong 3+ with all other single-dose cells on the panel. I called our reference lab, and they suggested that maybe there is a low-prevalence antigen on the cell causing steric hindrance. I noticed that the cell is also Le(a-b-), so maybe this is a cell from a black donor, and is more likely to have one of these pesky low prevalence antigens from the MN CHO collection. Any thoughts? Has anyone else noticed this? If so have you contacted Ortho?

Here is another option, if time permits. Perform a 1.5 to a 2 plasma volume exchange using 5% albumin as replacement fluid. Of course the problem is that there will still be residual Ab left, and hemolysis is still likely to occur. I also do not know how long a plasmapheresis procedure takes, but this could be an option for having a better chance at saving a Bombay that is not gushing blood . . . yet, when transfusion of incompatible blood is the only option.

Hi Mabel- The thought that I had was that the soluble A and B substance in AB plasma would create immune complexes with the patient's IgM Ab, which can bind autologous platelets and maybe even knock out the kidneys?? I'm not sure if this would even be a thought or a consideration in a massive transfusion situation.