Isohemagglutinin titers

[Sonya Martinez]

We have a very large heart transplant program which includes the possibility of giving an ABO incompatible (ABOi) heart to patients under 2 YO with low IgM and IgG Isohemagglutinin titers (generally <32).  Luckily all but one of the patient's listed for ABOi transplant have been given either type specific or type compatible hearts.  We have 4 different orders for isohemagglutinin titers; a simple backtype that we only perform during surgery to access the plasma and/or exchange transfusions by the perfusionists have dropped the antibody level down prior to the end of the transplant surgery, a 1:32 titer they can order if need a STAT result, a saline titer and an AHG titer.  Both the saline titer and the AHG titer are done at listing, every month until transplant, immediately pre-transplant and daily for days 2-7 post-operatively.  Recently we transplanted a patient listed for ABOi with a type specific, and therefore compatible, heart but our CTICU keeps ordering and collecting for the AHG titer for the last 4 days.  I've been cancelling and stating in the cancellation comments the test is not necessary for ABO compatible heart transplants but nothing has changed.  I personally don't believe there is and my medical director agrees with me.  Is there some other reason to perform either the saline or AHG titer on this patient?  (FYI:  we do not currently have a blood or lab test utilization committee and I've contacted the CTICU NPs and MDs in hopes they'll cancel their standing order.)

[mrmic]

Interesting issue.  I agree with what you have presented.  Trying to create communication with the transplant team is the best direction to go. In my past experiences with transplant/BB issues we found it better for the BB Supervisor and the BB medical director to meet with the Chief of the  transplant service.  Inquire why these tests are being ordered and why we are concerned about the tests being ordered.  If there was a reason the transplant physians were ordering these tests, maybe we could help them by suggesting the best laboratory tests to help achieve their goal.  (Research or treatment monitoring, etc.)

If the Chief of service agrees with your concerns regarding the testing, he/she will discuss with his transplant team.  Orders from the top - down within the service works best for getting the team to change their ordering practice.  

In addition, by offering the willingness of the laboratory to help the the transplant team accomplish their goal, if approved by the Chief of the service,  we (the laboratory) comes across as not to be telling what they are doing wrong but to offer our help to order the necessary, correct tests that would help their goal.

Good Luck

[mrmic]

As for why they might be ordering??? Just fyi..... I had only one interesting time which we followed these titers closely.  There were transplant physians studying the possibility of neutralizing the A and B antibodies that were incompatible with the transplanted heart with infusion of high doses of the corresponding sugar that represented the A or B antigen.  Later they also attempted to do the same with anti-species antibodies.  If memory serves me, these were conducted in the 1990s.  I believe the lead was Dr. D.K. Cooper. If anyone would like the references, I believe I still have some of the papers in a file cabinet.

[Malcolm Needs ☆]

I know that some of the early work on ABO-mismatched solid organ transplantation, viz-a-viz ABO antibodies was carried out by Professor Patrick Mollison and his co-workers, and he showed that, whereas inhibition of IgM ABO antibodies is reasonably easy by, in the early days, transfusion of FFP to adsorb the antibodies in vivo, the same is not true of IgG ABO antibodies.  He and his co-workers found the inhibition of these antibodies was much more difficult, and this was almost certainly because only 40% of IgG antibodies are intravascular, as so they "rebound" when inhibited or removed from the intravascular area, whereas almost all of the IgM antibodies are intravascular, and so "rebound" is less likely.