This study will assess how safe ABBV-154 is and how ABBV-154 moves through the body of adult healthy participants. Adverse Events will be assessed.

ABBV-154 is an investigational drug being developed for potential treatment of immune-mediated inflammatory diseases. Participants are randomly assigned to one of the 2 treatment groups. Approximately 40 adult healthy volunteers will be enrolled in 2 sites in the United States.

All participants will receive ABBV-154 as subcutaneous injections with one of the 2 different formulations.

There may be higher burden for participants in this trial. Participants will be confined for 9 days. Adverse Events and blood tests will be performed.

Inclusion Criteria:

- Body Mass Index (BMI) is ≥ 18.0 to ≤ 29.9 kg/m2 after rounding to the nearest tenth at screening and upon initial confinement.

Exclusion Criteria:

• Participant using any medications, vitamins and/or herbal supplements, within the 2 week period or 5 half-lives (whichever is longer) prior to study drug administration.
• History of epilepsy, any clinically significant cardiac, respiratory (except mild asthma), renal, hepatic, gastrointestinal, hematologic, demyelinating disease (including myelitis) or neurologic symptoms suggestive of demyelinating disease, glaucoma, psychiatric disease or disorder, or any uncontrolled medical illness.
• Prior exposure to similar biologic therapies.