The purpose of this study is to evaluate the safety and tolerability of single ascending dose of CNTO 7160 administered intravenously (IV) in healthy participants and multiple dose administered IV in participants with asthma and atopic dermatitis.

This is a Phase 1, randomized, placebo-controlled, multicenter study of CNTO 7160. The study consists of Screening Period, In-patient period (6 days for healthy participants, 11 days for asthmatic participants and atopic dermatitis participants) and outpatient period (105 days for healthy participants, 110 days for asthmatic and atopic dermatitis participants). The total duration of participation for each participant will be approximately 21 weeks for healthy participants, 25 weeks for asthmatic participants, and atopic dermatitis participants. All eligible participants will be randomly assigned to receive active agent or placebo. The study will be conducted in 2 parts. In Part 1, single ascending doses of CNTO 7160 or placebo will be administered to sequential cohorts of healthy participants as an IV infusion. In Part 2, ascending multiple doses of CNTO 7160 or placebo will be administered as IV infusions to sequential cohorts of participants with asthma or atopic dermatitis. Blood samples will be collected for assessment of pharmacokinetic and pharmacodynamics parameters in both part 1 and 2 parameters, along with assessment of safety and clinical effects in part 2. Participants' safety will be monitored throughout the study.

Inclusion Criteria:

• Part 1 (Healthy Participants): Participant must have a body weight in the range of 50 to 100 kilogram (kg) inclusive and have a body mass index (BMI) of 19 to 30 kilogram per meter square (kg/m^2) inclusive
• Part 1 (Healthy Participants): Participant must be healthy on the basis of physical examination, medical history, vital signs and 12-lead ECG performed at screening
• Part 2 (Asthma Participants): Participant must have a body weight in the range of 50 to 125 kg inclusive and have a BMI of 19 to 32 kg/m^2 inclusive
• Part 2 (Asthma Participants): Participant must have a physician documented diagnosis of asthma for at least 12 months before screening
• Part 2 (Atopic Dermatitis Participants): Participant must have a body weight in the range of 50 to 100 kg inclusive and have a BMI of 19 to 30 kg/m^2 inclusive
• Part 2 (Atopic Dermatitis Participants): Participant has physician documented diagnosis of atopic dermatitis for at least 12 months before screening based on UK refinements of the Rajka and Hanifin criteria

Exclusion Criteria:

• Part 1 (Healthy Participants): Participant has any known malignancy or history of malignancy, with the exception of basal cell carcinoma or squamous cell carcinoma in situ of the skin that has been treated with no evidence of recurrence within 6 months prior to the Screening Visit
• Part 1 (Healthy Participants): Participant currently has or has a history of any clinically significant cardiovascular disease, including but not limited to a history of angina or myocardial infarction, congestive heart failure, symptomatic atherosclerotic vascular disease, or arrhythmia.
• Part 2 (Asthma Participants): Participant has any known malignancy or history of malignancy, with the exception of basal cell carcinoma or squamous cell carcinoma in situ of the skin that has been treated with no evidence of recurrence within 6 months prior to the Screening Visit
• Part 2 (Asthma Participants): Participant has or have had a serious infection (eg, sepsis, pneumonia or pyelonephritis), or have been hospitalized or received IV antibiotics for a serious infection during the 4 months prior to the Screening Visit
• Part 2 (Atopic Dermatitis Participants): Participant has any known malignancy or history of malignancy, with the exception of basal cell carcinoma or squamous cell carcinoma in situ of the skin that has been treated with no evidence of recurrence within 6 months prior to the Screening Visit.
• Part 2 (Atopic Dermatitis Participants): Participant has or have had a serious infection (eg, sepsis, pneumonia or pyelonephritis), or have been hospitalized or received IV antibiotics for a serious infection during the 4 months prior to the Screening Visit