The purpose of this study is to assess the safety and tolerability of CNTO 5825 following a single intravenous (IV) or subcutaneous (SC) dose administration in healthy volunteers.

This is a randomized (study medication assigned by chance), placebo controlled, double-blind (neither physician or subject knows the name of the assigned study medication) study to assess the safety, tolerability, immune response, pharmacokinetics (what the body does to the drug), and pharmacodynamics (what the drug does to the body) of CNTO 5825. The study population will consist of 48 healthy volunteers and 16 healthy atopic volunteers. Five dose levels of study agent will be assessed. Participants will be required to stay at the research center after study agent administration for the inpatient portion of the study and then return for out-patient visits. Safety assessments will be performed throughout the study and include obtaining and evaluating laboratory tests, vital signs (e.g., blood pressure), and the occurrence and severity of adverse events. Placebo (containing inactive substances only) or one of five dose levels of CNTO 5825 will be given. Healthy volunteers will be given a single IV infusion (directly into a vein) or a single dose of up to 3 injections under the skin. Healthy atopic volunteers will be given one dose as as an IV infusion. There will be a screening period of up to 4 weeks. All participants will be in the study for 17 weeks after dose administration.

Inclusion Criteria:

• Healthy man or woman with no clinically significant abnormalities
• Body weight in the range of 50 to 100 kg inclusive
• Body mass index (BMI) of 18.5 to 30 kg/m2 inclusive
• For healthy atopic patients: history of atopic allergy

Exclusion Criteria:

• Known or suspected intolerance or hypersensitivity to any biologic medication or to any components of the formulation used in this study
• Received an experimental antibody or biologic therapy within the previous 6 months