Mine WBC hovers on the low end of normal...but I get monthly IVIG. During times I wasn't receiving IVIG, mine was borderline low, dipping down every now & then for no apparent reason (other than having autoimmune disorder).

That being said, I am primary immune deficient...and so are 25% of those with autoimmune disease (Sjogren's included).

Your visit with the hematologist will be interesting to hear what he has to say. He will likely run a large battery of labs for various things, just to see where this is coming from. Try not to read into what labs he runs (like for cancer, etc) because he's got to rule out everything (so it's not like he runs them thinking it will be positive).