Recently, we had a 49 years old female patient with leukemia and pancytopenia. In the past three months she had only been transfused with 6 unit of platelets at our hospital. According to the nurse, she had no red blood cells transfusion recently. She had not been pregnant. Last antibody screen was negative on Aug.25, 2014. On Sept.15, we received another sample and anti-E was detected from her sample. We could not figure out why this patient developed antibody. Could this anti-E be a passive antibody due to platelet transfusion? The reaction strength was 4+ with MTS panel. 

Another strange thing is that the tech. first did antibody screen on Galileo and got positive result. Then she did manual capture R panel which looked like anti-E and anti-c (patient's phenotype is E neg and c neg). The second technologist continued the work with setting up a MTS panel and it looked like  a straight forward anti-E. Due to the discrepancy from these two methodologies, we did the  third panel on Galileo and it came out as only anti-E. As I know, the first tech. who got anti-E and anti-c was dealing with another patient at the same time. Coincidently, her 2nd patient has the history of known anti-E and anti-c. However, the tech. sad she is 100% sure that she didn't mix up the two samples and actually the results (reaction strength) of two panels from these two patients looked a little bit different. My questions is that in your facility, if a patient developed anti-E and you know the patient is also c antigen negative, do you give the patient E- and c- negative blood or only E- negative unit?

Sorry for the long post. Thank you.

 

"If a patient developed anti-E and you know the patient is also c antigen negative, do you give the patient E- and c- negative blood or only E- negative unit?"

 

Yes, we would screen for both E and c neg units in these cases, since if the patient was exposed to E, they almost certianly have been exposed to c.

 

Scott

We do the same but it is partly because we are remote from our blood center and surrounded by smaller hospitals that don't do Ab IDs.  We think it is worth preserving the ability to give Rh neg blood in an emergency to a patient with anti-E, whereas if they also have anti-c already reacting strong enough to detect, there are fewer and poorer options.  Others will argue that it is not appropriate to use the limited c neg units on patients lacking the antibody.

_{I prefer to give little c neg if the patient is little c antigen negative to keep them from forming the antibody. When there is a little c most of the panel cells are positive and it can be harder to identify new antibodies if your supply of reagent red cells is limited.}

The antibody could have come from a number of sources.  Either there was anti-E in the plasma from the platelets (or maybe some Immune globulin that she was given at the same time?), or there were still some E+ red cells in the platelets that have stimulated the anti-E, or it isn't a real anti-E at all but a mimicking antibody.  OR - she WAS transfused between Aug 25th and Sept15th but somewhere else and this important piece of information was not passed on.  Might be useful to check the Hgb and RBC from the two dates!  Also, has she had an infection that might stimulate the production of an anti-E in this time?  I would be interested to know whether this antibody is IgG or IgM or a mixture of the two.  Do you have the possibility to test that?  Also, I would definitely re-test in a little while to see if it's still there.  If it's passive, it will have disappeared.

Galvania pretty much summed everything up. Considering that the reaction strength was 4+ how recent was the platelet transfusion?

 

For E-,c-neg patients with anti-E we provide E-,c-neg units in routine circumstances.

Remember that anti-E can often be naturally-occuring. I would say that is probably the most likely situation in this case, but regardless we would give R1R1 units at our facility.

Edited September 24, 201410 yr by Teristella

Could it be that she had an Anti-E from years ago that had fallen to undetectable levels recently (as they do) and then any RBCs in the platelets have triggered an immune response and brough the titre back up to detectable levels. I have seen many Anti-Es that subsequently go undetectable with time.