A Clinical Study Investigating OM-85-IN Safety and Tolerability in Healthy Volunteers and Mild Allergic Asthma Patients

Inclusion Criteria: 1. Male and female subjects aged 18 to 55 years. Women will be considered for inclusion if they are: * Not pregnant, as confirmed by pregnancy test, and not breastfeeding. * Of non-childbearing potential, or * Of childbearing potential and using a highly effective method of contraception . 2. Body mass index (BMI) ≥18 and ≤32 kg/m2. 3. Part II : History of mild asthma that is well controlled with Step 1 treatment according to GINA guidelines 2023 for at least 12 months prior to the Screening Visit, i.e., a history of respiratory symptoms such as wheeze, shortness of breath, chest tightness, cough, and limitation of airflow induced by aeroallergens. 4. Part II: Forced Expiratory Volume in the first second (FEV1) ≥80% of predicted at Screening Visit. 5. Part II : Positive skin prick test to common aeroallergens such as tree, weed, grass or house dust mites within 12 months prior to the Screening Visit 6. Part II : Production of adequate sputum with ≥2 x 105 total non-squamous cells within 12 months to 2 weeks prior to V1A (Day -8) 7. Part II : Positive reaction to Nasal Allergen Challenge (NAC) within 12 months to 2 weeks prior to baseline Exclusion criteria: 1. Any clinically relevant abnormal findings in physical examination, clinical chemistry, haematology, urinalysis, vital signs, lung function or electrocardiogram (ECG) at Screening Visit, which, in the opinion of the Investigator, may either put the subject at risk because ofvparticipation in the study or may influence the results of the study, or the subject's ability to participate in the study." 2. Use of prohibited medication prior to study enrolment 3. Part II - Long-term, daily treatment with inhaled corticosteroids. 4. Part II - Exacerbation of asthma defined according to the GINA guideline 2023 as a progressive increase in symptoms of shortness of breath, cough, wheezing or chest tightness and progressive decrease in lung function, i.e., they represent a change from the patient's usual status that is sufficient to require treatment changes within 1 month prior to the Screening Visit. 5. Part II - Concomitant allergies to seasonal aeroallergens which are anticipated to be or become active during study participation. 6. Known allergy to IMP active substance and/or excipients or the challenge agent components. 7. Specific immunotherapy in the past 3 years before Baseline, ongoing treatment with any specific immunotherapy or plan to receive such treatment during study participation. 8. Previous or ongoing treatment with other bacterial lysates and/or probiotics (dietary supplements, medicinal products and/or other health products) within 30 days before Baseline. 9. Patients with pathological skin modifications in the test area (e.g., acute or chronic eczema or skin infections), with disturbed skin reactivity (e.g., hyperkeratosis, ichthyosis, urticaria factitial), or with acute, generalized hypersensitivity reactions. 10. Participation in any other clinical study within 30 days prior to Screening. 11. Past or present disease, which as judged by the Investigator, may affect the outcome of this study. 12. Positive serology test for hepatitis B surface antigen (HBsAg), hepatitis B core antibodies, hepatitis C virus antibodies (HCV-Ab) or human immunodeficiency virus (HIV) antibody at Screening Visit 13. History or presence of clinically significant hypertension 14. History of anaphylactic shock, generalised exanthema, angioedema or hypotension caused by the allergen used for NAC, or any medicinal product in the past. 15. History of drug or alcohol abuse in the past 12 months. 16. Current smokers or ex-smokers for less than 6 months or more than 10 pack years. Current vapers (users of e-cigarette products) or ex-vapers for less than 6 months. 17. Part II : Negative reaction in the baseline NAC