Hi @andreak78 It’s good to hear from you! The first several months after a BMT, (actually the first year) can be a bit of a roller coaster ride with fluctuations with some blood numbers and possible flares of GVHD. Steroids can impact blood counts, lowering them. So you may see some increase in the blood counts as you wean off the steroids.

It’s certainly understandable to feel concern seeing the chimerism number decreasing. That’s the reason your team has decreased your tacro dosage. Let me explain. When we have the BMT, the goal is to have 100% engraftment from our donor. (0% recipient/100% donor). It doesn’t always happen that way but that’s the goal. When those numbers don’t reach 100% or start backsliding, doctors may adjust the tacro to a lower dosage so that more of a reaction with the new cells take place. Basically, allowing the newer aggressive, healthy cells to overtake the remaining old cells.

Tacrolimus is immunosuppressive agent that functions as an effective anti-inflammatory medication. Your new stem cells (the graft) are producing new blood cells. A great part of these become white blood cells whose job is to create a ‘force field’ against infections, viruses, or other invaders. Because they are comprising your new immune system, they are very aggressive by nature. And when they are introduced into a foreign body, such as yours (the host), they tend to want to launch a defensive attack against that huge organism! (GVHD). The tacro, being an immunosuppressant, holds those aggressive cells back a little, calms them down until the new adaptive immune system begins to recognize your body as friend, not foe! Eventually the cells and your body learn to play well together! ☺️
Initially, if the new cells are held back too much then there may be an opportunity for your old cells to start replicating. By reducing the level of Tacro, this allows for a more aggressive response from the new cells. Your doctors are hoping to see your chimerism climb with this reduction in tacro.

If that doesn’t work there are other options such as a DLI. That’s a donor leukocyte infusion. Healthy white blood cells from your donor would be infused into your blood as a boost. This is often done if there is a mixed chimerism of your old cells and donor cells.

Here’s a good article from Cleveland Clinic with how that works. https://my.clevelandclinic.org/health/treatments/10343-donor-leukocyte-infusion

When is your next set of labs/STR CD3 test? I’m sure you’ll be on pins and needles until you get that new reading. But these situations do happen and are usually readily taken care of.

Have you mentioned your heart rate changes to your BMT team?