T+35 Pollywogs and Chimerism

BOX SCORE
Element	Current	Std. Range	Trend
Hemoglobin	10.5	13-17	v
Platelets	163	140-375	^
ANC	2540	1800-8300	v

When I was a boy of about 7 to 10 years old, my pals and I used to go down the hill to "The Swamp." The Swamp was a kind of a mire down in a gully. I'm not sure what the source of the water was, perhaps just accumulated rainfall. This was, after all in suburban Portland, Oregon. 

Anyway, as young boys are wont to do, we would go to The Swamp to explore. In the spring we would often find pollywogs. I don't know why, but whereas my friends often took home jars with pollywogs in them to watch them turn into frogs, I did not until much later in the season. I finally did gather a half dozen or so of the little wigglers and took them home. I fed them and watched them...and watched them...and watched them. 

My friends' pollywogs had all long since grown legs and were slowly absorbing their tails and looking very much like the adult frogs they would eventually become. Although my pollywogs grew larger, they didn't seem to change shape. One day about six months into this journey, a friend of my father's came over to visit. He noticed the pollywog jar and asked how their development was coming along. I told him it wasn't. Although I had had them for six months, they just got bigger; they  didn't seem to want to turn into frogs. 

Mr. H said, "The reason is that these are Bullfrog pollywogs. They take two years to mature into frogs!" I was dumbfounded. I was disappointed. I was crestfallen. Two years? I didn't have two years to waste watching big fat pollywogs turn into Bullfrogs. My discouragement was such, and Mom's weariness of having pollywogs in the dinette was such that, when she told me to dispose of them, I promptly took them back to The Swamp. 

Waiting for change is hard, especially when those around you have waited so much shorter a time for a similar change to occur. My friends had watched their pollywogs turn into frogs and got bored with the frogs. But at least I learned something about frogs, which I remember to this day! 

We have been waiting to learn something definitive about the status of my bone marrow transplant. Today is day T+35, a big day in a couple of ways. First of all, it is the final day of my taking six horse pills a day of one of the anti-GVHD* medications I have been taking. This is a landmark of sorts, because it indicates progress toward the goal of reducing dependency on medicine to keep me healthy and increasing dependency on my new immune system. 

It also happens to be a landmark day, because we received the first results of the bone marrow biopsy (BMT) I had on Monday, day T+33. This result is based on microscopic examination of the marrow cells. The pathologist looks for a couple of indications of the progress of what is known as "chimerism."** In the case of transplant oncology, a chimera is a body composed of diverse DNA sources. In other words, the pathologist is looking to see how my DNA is getting along with the donor DNA. 

In this part of the interpretation of the BMT, they look for two kinds of cells: CD3 cells and CD33 cells. CD3 cells are T-cells, which are part of the immune system, and CD33 cells are myeloid marrow cells. The readout is reported in terms of what percentage of each cell type is from the donor tissue. 

In this report, they looked at 23,000 CD3 cells and 150,000 CD33 cells. The good news is that 99% of the CD3 cells were from the donor stem cells, and 100% of the CD33 cells were from the donor stem cells. This is very good news, if I (a retired, unlicensed, recovering dentist) understand my hematology. It suggests that the transplanted cells have taken over my bone marrow. In particular, I am encouraged that 100% of the CD33, or myeloid, cells are from the donor. Remember we have been dealing with Acute Myeloid Leukemia. My leukemia cells are derived from myeloid precursors. Now the myeloid precursors are coming from the donor tissue, which is presumably free of leukemia. (Before you run to the media outlets to report all of this, you might want to wait until I confirm it all with Dr. Meyers on Friday.)

So, some of the waiting is over and has resulted in anticipated changes being observed, unlike my stint with the pollywogs. Assuming that my understanding of the hematology involved is correct, and that may be a large assumption, we couldn't be more grateful and pleased. 

May God himself, the God of peace, sanctify you through and through. May your whole spirit, soul and body be kept blameless at the coming of our Lord Jesus Christ. (1 Thessalonians 5:23)

*GVHD: Graft Versus Host Disease - the tendency for the grafted cells to attack host cells.  

**Chimerism: Derived from the word Chimera, meaning "an imaginary monster compounded of incongruous parts."