The treatment of allergic contact dermatitis (ACD) can be unsatisfactory, and that other skin diseases such as atopic dermatitis have an increased likelihood of ACD, improved systemic treatments are needed.

This research study explores the effectiveness of Baricitinib in treating Delayed-Type Hypersensitivity (allergic) versus Irritant Skin reactions. Subjects for this study need to be healthy males between the ages of 18 and 40. This study will evaluate this by injecting antigens as well as applying them on top of the skin to the forearm then measure the effects of Baricitinib by skin and blood testing.

Inclusion Criteria:

• Males 18-40 years of age at the time of signing the informed consent document
• Understand and voluntarily sign an informed consent document prior to any study related assessments/procedures being conducted
• Able to adhere to the study visit schedule and other protocol requirements
• Must be in good health as judged by the Investigator, based on medical history and physical examination, and no laboratory abnormalities

Exclusion Criteria:

• Any known severe allergies to yeast products
• Currently active skin diseases such as psoriasis, atopic dermatitis, allergic contact dermatitis or irritant contact dermatitis
• Inability to understand informed consent
• Any medical condition that the investigator feels would interfere with study
• Any abnormalities on physical exam or screening laboratory studies (to progress to Part II)
• Agree to discontinue use of prohibited medications at least 4 weeks prior to screening:

topical corticosteroids, oral or injectable systemic steroids, systemic immunomodulators (cyclosporine, methotrexate, etc.), oral or topical antihistamines

• Positive reaction to tuberculin test (PPD) or negative control
• Negative reaction to initial skin testing for Candida, Trichophyton, or Sodium Laurel Sulfate