Yes, WBC's decrease in number during a fast. Your body overproduces wbc's to what we call "normal" range between ~ 4,000 - 11,000 per microliter of blood. Fasting leads to a draw down of the older less viable cells for their parts (protein), but plenty of wbc's remain for immune function - in fact, what remains are in a better position to fight disease.
The recycled wbc proteins are used in combination with fat (glycerol) obtained from your "fat" to make the minimal amount of sugar (glucose) your body always has to have (about 70 ng/ml) circulating at all times which is about 4 grams (for a 70 kg person). Imagine the amount of sugar via carbs you eat every day. A lot more than 4 grams. What this means is that carbs are intended truly for one purpose - to get you fat. Insulin drives carbs to fat tissue when carbs are ingested. That is really what insulin is for - to make you fat so you can survive famine. During feast times hundreds of years ago (i.e. maple syrup running up the tree, fruits forming, lots of carbs are plentiful) carbs are available only for a short time. Your body craves them when available and eat all you can to fatten up. Then when carbs are gone - fruit has fallen, leaves are no more, only fat in the form of nuts are available. The body's insulin drops and fat is released to provide energy. White blood cells (of which you have pounds of them) become a store of protein to provide the raw ingredients with glycerol to make a few grams of sugar to keep red blood cells working and other small needs. Cycle of feast and famine.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2636990/
All I am doing with this fast is putting my body through this cycle so all of my biochemical machinery is maintained. I had no headaches this time around - no so-called keto flu. With knowledge, I understand what my body is going through and how to minimize the discomfort. We really are designed to go without food - and when food is plenty - to eat and eat and eat. The problem in our culture today (primarily west) is that we have carbs available all of the time. So our fat burning machinery goes dormant. The first time you do what I did - your fat burning chemistry has to activate - that takes 24-36 hours - hence the headaches and fatigue. I went through that the first time I did this - not this time!
Now that my wbc's are reduced - signals are sent to the bone marrow to the stem cells to replicate and get busy. Once I start to eat, that will trigger white blood cell creation in large numbers to restore WBC's to normal levels which will take a few days. It is during this time of stem cell activation that the 'hiding' leukemic stem cells come out to divide and get killed by sprycel thereby reducing my residual LSC population. Hopefully this reduces to such an extent that when I try stopping sprycel, my CML is functionally destroyed. I'll never know if this works - even if I have successful treatment free remission. It's just my working theory. And - losing a few pounds of body fat in the process is o.k. too.