The main aim of this study is to assess the safety, tolerability, pharmacokinetics (PK), immunogenicity and pharmacodynamics (PD) of single ascending doses of LAD106 (Part A) and multiple ascending doses of LAD106 (Part B) in human healthy participants.

This is a 2-part study. Part A will comprise up to 6 cohorts of healthy adult participants and investigate single ascending doses of LAD106. Part B will comprise up to 3 cohorts of healthy adult participants to evaluate multiple ascending doses of LAD106, and 1 cohort will investigate the pharmacodynamic effects of lebrikizumab. The study is based on sequential cohorts for escalation of single and multiple doses of LAD106, where progression to the next cohort is only started following a review of safety, tolerability, and pharmacokinetic data of earlier study cohorts.

Inclusion Criteria:

1. Signed informed consent and willing and able to comply with the study protocol.
2. Healthy men or women,18 to 45 years of age (inclusive) at screening.
3. Female participants agree to use effective contraception.
4. Male volunteers agree to use barrier protection when they engage in sexual relations with women of child-bearing potential (WOCBP) or lactating women.
5. Body mass index (BMI) between 18 and 32 kilograms per square meter (kg/m^2), inclusive, and with a minimum bodyweight of 50 kg.
6. Has the ability to communicate well with the Investigator in Dutch language and willing to comply with the study restrictions.

Exclusion Criteria:

1. Evidence of any active or chronic disease or condition that could interfere with, or for which the treatment of might interfere with, the conduct of the study, or that would pose an unacceptable risk to the participant in the opinion of the investigator.
2. Clinically significant abnormalities, as judged by the Investigator, in laboratory test results.
3. Use of any medications (prescription or over-the-counter [OTC]), within 14 days prior to IMP dosing or less than 5 half-lives (whichever is longer). An exception is made for paracetamol (up to 4 g/day).
4. If a woman, pregnant, or breast-feeding, or planning to become pregnant during the study.