Following a screening period of a maximum of 28 days, subjects will stay at the study facility for eight nights starting from the day before dosing (Day -1) to Day 8. The follow up period after the dosing will be 84 days (112 days for cohort 3). Subjects will receive a single dose of MEDI9929 or placebo subcutaneously on Day 1 and safety monitoring and serial collection of blood samples for PK evaluation will be followed throughout the study period.