This study compares the potential immunogenicity of two filgrastims, the proposed biosimilar Filgrastim Hospira (US) and the US-approved Neupogen reference product. Subjects will receive doses of one of the two filgrastims by injection of 5 micrograms/kilogram (mcg/kg). Subjects will receive 5 consecutive daily doses in Period 1 (Days 1-5) and a single dose on Day 1 of Period 2. Pre-dose and serial post-dose assessments of immunogenicity will be conducted each of the two study periods. In addition, safety assessments will be conducted throughout the study.