A Study to Evaluate Use of Induced Skin Blisters in Adult Participants With Atopic Dermatitis, Allergic Asthma and Atopic Healthy Participants

This is an interventional (a treatment given during the course of a research study) and multicenter (when more than one hospital or medical school team work on a medical research study) study. The study will consist of 3 Phases: Screening Phase (Up to 4 weeks), Data Collection Phase (9 days) and, Follow-up Phase (7 days). The maximum study duration for each participant will not exceed 43 days. Primarily, the cell populations and inflammatory mediator responses in suction skin blister fluid after allergic skin reaction (ASR) will be assessed. Participants' safety will be monitored throughout the study.

Inclusion criteria

• Participant must have signed an informed consent document prior to any study related procedures indicating that they understand the purpose of and procedures required for the study and are willing to participate in the study
• Participant must be willing/able to adhere to the study visit schedule and other requirements, prohibitions and restrictions specified in this protocol

• For participants with Asthma:
• Participant must have a physician documented diagnosis of asthma for at least 12 months before Screening
• Participant must have an Asthma Control Questionnaire 6 (ACQ6) less than (<) 1.5 at Screening

• For participants with Atopic Dermatitis:
• Participant must have a physician documented diagnosis of atopic dermatitis for at least 12 months before Screening based on UK refinement of the Hanifin and Rajka's diagnostic criteria
• Participant must have atopic dermatitis with and Investigators Global Assessment (IGA) score of 2 to 4 at Screening

Exclusion criteria

• Participant has taken any prohibited or restricted medications as noted below under Prestudy and Concomitant Therapy
• Participant has received an investigational drug (including investigational vaccines) or used an invasive investigational medical device within 6 weeks or 5 half-lives (whichever is longer) before the Screening visit

• For participants with Asthma:
• Participant has a history of life-threatening asthma, defined as a history of respiratory arrest or requiring intubation for asthma
• Participant had been admitted to a hospital for asthma in the 1 year before Screening

• For participants with Atopic Dermatitis:
• Participant has evidence of any other skin condition that would interfere with assessment of Atopic Dermatitis (AD)
• Participant has active AD related infection or has had an active AD infection within 2 weeks of Screening (participants with evidence of colonization on skin swab testing but with no infection are allowed)