From the series of Doctor Dolittle children’s books, a creature called the pushmi-pullyu is introduced. It is a gazelle/unicorn cross with two heads, one head at each end of its body. The pushmi-pullyu usually only uses one of its heads to talk, reserving the other for eating (thus allowing it to eat while speaking without being rude) and claims that its great-grandfather was the last unicorn. In the 1967 classic movie “Doctor Dolittle,” the pushmi-pullyu is presented as a two headed llama.
After my bone marrow/stem cell transplant, one of the primary concerns is graft versus host disease. You have probably heard of graft rejection where something like a kidney is transplanted and the concern is that the body will reject the graft. In such a case the body’s immune system attacks the transplanted kidney as a foreign object. In the case of graft versus host disease (GVHD), the transplanted stem cells grow an immune system that may see the entire body as foreign and begin to attack it. There are typical areas that GVHD is most likely to happen and there are varying severities of GVHD. Most doctors say that a little GVHD can be an indicator that the new immune system will be more likely to kill any subsequent cancer cells.
Enter Tacrolimus or “tac,” as it is frequently referred to in the biz., is the current preferred immunosuppressive medication for BMT patients. See my previous post on how this medication got its name 😉 So, with a new immune system, it is difficult to know just how it will interact with the host. As such, tac, is used to put the reins on the new immune system. You can guess that there needs to be a balance, and it can be delicate. Too much tac could mean an ineffective immune system. To little tac could mean serious GVHD issues. When I began to understood this initially counterintuitive system, the first picture that popped into my mind was the pushmi-pullyu. When I was in my childhood and first introduced to the pushmi-pullyu, I found it to be oddly confounding yet intriguing. I feel similarly about Tacrolimus.
Thank you for your continued prayers, love and support. God bless you!