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Dropping chimerism

Hi looking for some advice from anyone who has experience of dropping chimerism 3/4 years post transplant?.

My daughter had a BMT to treat refractory ALL in 2017. Although her bone marrow always been a bit fragile. Mild pancytopenia and only 40% graft marrow cellarity. She always had 100% chimerism until about 18 months ago. It started only in the myeloid cell lineage and has been dropping very slowly but dropping nonetheless. She's now at 82% donor,18% self chimerism for myeloid.

But now the lymphoid is dropping too sitting at 97% last check.

We were told DLI isn't an option as it was myeloid that dropped first.

Trouble is now my daughter has said she doesn't want it checked anymore, doesn't go to appointments and doesn't want to know . I've tried to intervene but she's 21 now so I have no authority. I'm pretty terrified.

I'm worried about cancer obviously but my immediate concern is that her donor marrow is O neg, O neg cells don't react but they make anti a and anti b antibodies in plasma right????

Her retuning marrow will be making A+ blood cells. So there will come a point when there will be across reaction if myeloid continues to drop, the anti A antibodies in plasma will go for her A+ blood cells??

Without seeing her consultants I can't ask and she doesn't want to know??

How can this be treated? Does anyone have experience ????


  • Hi there and thanks for posting. I'm one of the online community champions and had a stem cell transplant myself for ALL 9 years ago. You've given a lot of technical information which I don't fully understand but hopefully someone from the Anthony Nolan team can help with that information.

    I have seen a number of posts from people concerned about dropping chimerism so it can and does happen, though I think most of the posts have been concerns around less mature transplants when chimerism is often affected by infections early in engraftment. I think I also recall that not everybody achieves 100% donor chimerism and some patients do have some of their original remaining so it may not necessarily be an issue if it remains stable.

    I guess the worrying thing is that your daughter doesn't want to have it checked and will not go to appointments. She is probably worried about what the cause might be and have to go through more treatment. At the age she is at I suppose you can't force her to go, but she will hopefully see how worried you are and will make the decision to find out. It is probably better to find out early rather than linger and let the chimerism drop further, if indeed it is dropping.

    I can tell from your post that you are obviously worried. If you need to talk to someone about your worries my advace would be to call the Anthony Nolan telephone emotional support on 0303 303 0303 and speak to someone about your concerns. They provide support to parents and families as well as patients and may be able to help give you some assurances.

    I'm sorry I can't give you more specific advice, but the Anthony Nolan team are better placed to do that. In the meantime I hope your daughter stays healthy and decides to make an appointment to get some answers that will hopefully put your mind at rest.

    All the best


  • Hi @Moirplace,
    I'm Rachel- Lead Nurse here at Anthony Nolan.
    A mixed chimerism is not an unusual scenario but, as you state, the continued monitoring of the chimerism is really important post transplant. From what you have stated in your post, the ABO mismatch that has occurred between your daughter and her donor is a minor one, these mismatches occur in approximately 20% of Stem Cell Transplants and shouldn't be of major concern at this point post transplant (I'm not sure how far out from transplant she is but it sounds like a good couple of years). A minor ABO mismatch in the early, post transplant phase, can cause some complications with blood cell destruction but all Transplant Centres will follow a procedure for appropriate transfusion of blood, platelets and plasma post transplant and will continue this until chimerism stability has been achieved.
    I hope this has gone some way to answering your query- If you'd like to discuss anything further please do call our helpline: 0303 303 0303.
    Kind regards

  • Hello Moirplace

    My name is Michelle, like Steve, I am an online community champion and a SCT recipient.

    I had my transplant in 2019 and very early on my chimerism did not climb, i had a response that isn't seen that often, and due to my limited level of consciousness at the time, I can't recall medical statuses other than my body didn't take the donor cells very well and I had a big miss match. However, due to this being in the very early stages, first 2 weeks, I was given lots of blood and platelet transfusions to maintain things, enough, until I could receive a stem cell top-up. I received this and in time my chimerism increased.

    I hear that your daughters are falling and is having other clinical signs of changing numbers which I cannot comment on I'm affraid, but specificaly relating to chimerism, I have heard of patients experiencing this. When I spoke with my team about the risks of chimerism falling, I was assured that there is a threshold for what would be considered as 'needing' treatment and it would depend on any other blood work numbers too. In isolation falling chimerism isn't a huge indicator for immenent problems.

    However, I'm not best placed to answer the enterity of your concerns, sorry I can't be ore helpful. I hope knowing that falling levels doesn't mean immenent 'bad news'.

    In respect to your daughters desire to not attend appointments she is probably feeling overwhelmed and anxious about the prospect of any problems and having to endure more treatment. Any change can trigger overwhelming thoughts of 'what if?' And sometimes people chose to not approach it. Being gentle and encouraging about the idea of attending appointments can help but also trying to find away in getting her to open up about why she won't engage at the moment. As a young person she may be experiencing thoughts around not wanting to 'lose' the life she is building in regards to social life, work, education, there may be negative association with hospitals, treatment, appointments.

    I hope your able to find a way to encourage her to consider exploring what is going on, and that in the mean time you and her could get support from Athony Nolans emotional support line, as previously quoted. It might help her to speak to someone not directly involved

    Hoping all goes OK and please continue to speak with us here or phone the number provided for continued support during this time.

    Best wishes


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