Why is my white blood cell count low?

Here is My Question:
My neuro is planning Rituximab for me and I have got all the tests prescribed by him done. Everything is normal, I have even taken the vaccinations he advised me to but the WBC test wasn't normal in the sense that my WBC or TLC count came out to be low each time I got it done (the values being 3900 and 4400, wherein the B cell count was high which anyways would get depleted after the infusion leaving me with very little immune system to fight any possible infections in case my WBC count remained low) and my doctor has advised me to wait for the count to normalize. But why it is low at the very first place (as I have been drug-free for the past 1.5 years) ? I mean a period that long is good enough for wash out.

Answer:
There are many reasons for a mildly low white blood cell count (WBC). The numbers you provide (3900 and 4400) are actually fairly normal WBC.

You didn’t actual provide a total lymphocyte count (TLC), so I can not comment on whether that count is low.

Revere (Rip) Kinkel MD
Professor of Clinical Neurosciences
Director of the Multiple Sclerosis Program
Clinical Neurosciences Director
University of California San Diego