I have the same issue- I've had low WBC count for 3 yrs (as well as hormonal & digestive issues) that none of my doctors have been able to figure out. And, it's only dropped & dropped over the years, my doctor only said it looked like my body was fighting a serious infection that she couldn't find. I did my first parasite cleanse a few months ago & found out I have a serious parasite problem. I'm on my second round of Hulda Clark herbs now, still have parasites, still have low WBC count. And, I'm worried unless I can raise my WBC count, my body will never be able to clear these parasites. Researching Hulda Clark's books, she recommends using Germanium + rose hips (for the vitamin C & bioflavanoids I assume) + selenium to raise WBC count. I'm already taking high doses of vitamin C as well as supplementing w/Selenium - I just ordered Jarrow Formula's organic Germanium Ge-132 (never use the inorganic form) so I'm going to try that out: some of the science about organic germanium sesquioxide Ge-132 bolstering the immune system is very interesting.
But there's not alot of info about raising WBC count out there.
I also think it's directly linked to a parasitic infection: I don't know which came first either- if the parasites were allowed to take hold because the white blood cell count was low or if they're the ones who lowered it.