• INCLUSION CRITERIA:
• Healthy individual aged 18 to 60 years.
• No active infection or history of recurrent infection.
• Normal renal function: creatinine <1.5 mg/dL or estimated glomerular filtration rate (eGFR) >=60 mL/min/1.73 m^2, with no significant proteinuria.

Normal liver function: bilirubin <2.0 mg/dL (when unconjugated), transaminases <2.0x ULN in the absence of known liver disease.

Normal blood count: WBC 2,500-11,000/microliter, ANC >1,500/microliter, platelets >150,000/microliter, hemoglobin >12.0 g/dL.

• Normal cardiovascular function, no history of chest pain, myocardial infarction, peripheral vascular disease, transient ischemic attack, or stroke.
• Healthy female subjects of childbearing age should have a negative serum pregnancy test with one week of beginning G-CSF administration.
• Female subjects should not be lactating.
• Subject must be eligible for normal blood donation. He or she must be tested negative for syphilis (RPR), hepatitis B and C (HBsAg, Anti-HBc, Anti-HCV), HIV, HTLV-1, West Nile virus, T. Cruzi and Babesia test.
• Subject must be able to comprehend the investigational nature of the study and provide informed consent to participate in the protocol.
• Antecubital veins must be adequate for peripheral access during apheresis. Potential participants must be screened by an apheresis nurse to check venous access before protocol entry.

EXCLUSION CRITERIA:

• Active viral, bacterial, fungal or parasite infection.
• Female with positive pregnancy test or lactating.
• Active or moderate-to-severe autoimmune disease that is currently treated or expected to require immunosuppressive therapy. Candidates with stable, well-controlled mild autoimmune disease may be considered on a case-by-case basis.
• Active or recent malignancy within the past 5 years. Individuals with remote (>5 years) histories of low-risk malignancies in remission (e.g., localized prostate cancer) or treated basal cell carcinoma may be included.
• History of any hematologic disorders.
• History of clinically significant cardiovascular disease (e.g., symptomatic coronary artery disease, uncontrolled hypertension). Minor risk factors must be evaluated on a case-by-case basis (e.g., controlled hypertension).
• Any positive serum screening test as listed in eligibility.
• Allergy to G-CSF or bacterial E coli products.
• Administration of NSAID within. 5-7 days of starting the protocol, depending on drug half-life.
• History of G-CSF administration and leukapheresis within past 3 months.