Age 18 or greater.
Normal renal function: creatinine less than1.5 mg/dL, proteinuria less than1+.
Normal liver function: bilirubin less than 2.5 mg/dL, ALT less than 2.5 times the upper limit of normal, all other transminases less than 2.5 times the upper limit of normal.
Normal blood counts: WBC 3,000-10,000/mm3, granulocytes greater than 1,500/mm3, platelets greater than 150,000/mm3, hemoglobin greater than 12.5g/dL, MCV within normal limits.
Female volunteers of childbearing age should have a negative serum pregnancy test within one week of beginning G-CSF administration.
Meets NIH Department of Transfusion Medicine (DTM) eligibility criteria for blood component donation for in vitro research use (negative serologic tests for syphilis, hepatitis B and C, HIV, and HTLV-1).
Ability to give informed consent to participate in the protocol.
Any underlying hematologic disorder including sickle cell disease.
Active viral, bacterial, fungal, or parasitic infection.
History of autoimmune disease, such as rheumatoid arthritis or systemic lupus erythematosus.
History of cancer excluding squamous carcinoma of the skin and cervical carcinoma in situ.
History of cardiovascular disease or related symptoms such as chest pain or shortness of breath.
Any positive serum screening test as listed below.
Allergy to G-CSF or bacterial E. coli products.
Splenic enlargement at baseline on ultrasound.