Antibodies and Alleles and GVHD, Oh, My!

BOX SCORE
Element	Current	Std. Range	Trend
Hemoglobin	7.8	13-17	^
Platelets	52	140-375	^
ANC	2400	1800-8300	^

Have you ever thought about how important information is? I mean, duh, we have to have information to make decisions. Then again,  I have seen some people make decisions that I'm convinced must have been made with a coin toss or an eeny, meeny, miney, moh process. You know the type...the ones that make you ask, what were you thinking? Or were you even? 

We just had a Zoom meeting with Dr. Meyers, the geriatric bone marrow transplant oncologist at Oregon Health and Science University (OHSU). Our previous meeting with Dr. Meyers was an in person appointment at OHSU. I think both Jill and I came away from that one feeling as if we had been drinking from a fire hose. Trying to process so much information in such a short time was overwhelming. But, we also came away from that meeting with some books that explain much of what Dr. Meyers told us and more in written form. For me that is much better, because I can process it in smaller bites. The outcome of reading that literature is that going into today's meeting, I had been able to formulate some intelligent questions. 

If you would like to review the post I wrote after the first meeting with Dr. Meyers it was "A Cat Among The Pigeons." In that post, I mentioned that the latest poop on donor matching is that the medical community has learned there are 8 genetic markers (not the previously accepted 10) that must be considered in matching a donor to a Bone Marrow Transplant (BMT) recipient.  A perfect match would obviously be 8/8, but we were told that technology has provided the option of using a 7/8 donor match with good success. 

During today's meeting we learned that, following an antibody study of my blood and a new search of the donor database, some 500 potential 7/8 donor matches were identified. We also learned that, when there is a mismatch, there are two possible kinds of mismatch. The first of these is an antigen mismatch. Essentially, this amounts to the recipient possessing antibodies that would attack certain proteins in the donor cells, much like antibodies attack germs that get into our systems in order to protect us from disease. Antibodies don't know that the transplant cells are "good guys." So, they dutifully attack them to "protect" the patient from these foreign cells. 

The other type of mismatch is called an allele mismatch. Now I want you to pay close attention here...you know, for the quiz. An allele is "any of the alternative forms of a gene that may occur at a given locus."* What the? I'm going to the registrar's office and drop this course. No, no, wait. In plain English what that means is that human genes (you know the guys that decide whether you have blue eyes or big feet) can take different forms in different folks. That's why some people have blue eyes and some have brown, while others have big feet or not.

According to Dr. Meyers, an allele mismatch is much less likely to cause a problem called Graft Versus Host Disease (GVHD), and that's a good thing, because GVHD can be controlled with medications, but there are limits. So, the less severe GVHD is, the easier it is to control. And what, you may ask, is GVHD? Well, it's kind of like the antibody/antigen problem, only in reverse. In GVHD, the donated cells decide the recipient's cells are a threat, so they try to eliminate them. 

Oddly enough, part of the transplant process is aided by GVHD. Because it is impossible to tell clinically whether every last one of the leukemia cells has been eliminated during the pre-BMT preparation of the patient, a little GVHD can kill them off, along with any remaining host marrow cells that could produce new leukemia cells. On the other hand too much GVHD can wreak havoc on the patient's body. Think of it this way, a nice glass of wine can help you relax at the end of a busy day, but if you drink the whole bottle you're gonna have an aching head in the morning. (And probably be late for work!)

OK, enough of the scientific malarkey. Let's get down to cases. Dr. Meyers told us that of the 500 potential 7/8 mismatched donors, three are allele mismatches. Now just because a person's name and genetic profile are on the donor database does not guarantee that he or she is going to be a donor. We have several friends who have been on the BeTheMatch.org donor database for several years without being called upon to donate stem cells. After that much time, people's circumstances can change. Maybe they are no longer interested in donating. Maybe they have become ill and can't donate. What I'm saying here is that 3 donors is a slim field, and it is not a slam dunk that one of these persons will be willing and able to donate. So, for those of you who like to pray, you might put this little piece on your prayer list. 

I had a list of twenty-one questions for Dr. Meyers. She answered them all with confidence and clarity, which boosted my confidence and, I think, Jill's. This is a hard decision, because there is a downside to transplant. In addition to the hope of a longer, leukemia free lifespan, there is the likelihood of some pretty dismal days during the process and the possibility of some nasty consequences due to GVHD, if it should be the kind that can't be easily controlled with medication. As I wrote in a previous post, titled "Walking with My Abba Father," 

"What I know from much time spent in prayer and perusing the Scriptures, is that God has been faithful to me throughout my life, even when I was unfaithful to Him. (See Romans 5:8) Most recently I have come through almost three years of a battle with cancer that has left me mostly unscathed, thanks to God's faithfulness. So, I believe I can confidently walk through whatever doors He opens as we walk together into the future."

*https://www.merriam-webster.com/dictionary/allele