Monocyte levels, in particular, are seen decreased when patients are on prednisone. Outside of that, WBCs overall are depressed in these conditions:
- overwhelming infections
- dietary deficiencies
- some drug toxicities
- autoimmune diseases
- bone marrow failure
- bone marrow inflitration (myelofibrosis)
http://www.webmd.com/hw/lab_tests/hw4260.asp - about CBC