Non-interventional Translational Study in Mild, Moderate and Severe Acne Patients

INCLUSION CRITERIA: AGE I01: Aged 18 to 25 years on the day of inclusion. TYPE OF PARTICIPANT AND DISEASE CHARACTERISTICS I02: Participants with a formal diagnosis of either: * Mild facial acne vulgaris defined as Investigator's Global Assessment (IGA) of 2, or * Moderate facial acne vulgaris defined as IGA score of 3, or * Severe facial acne vulgaris defined as IGA score of 4, or * Healthy volunteers without acne defined as IGA score of 0. INFORMED CONSENT I03: Informed consent form has been signed and dated by participant capable of providing informed consent. Note: For minor participants, informed consent form must also be signed and dated by the parent(s) or another legally acceptable representative(s). OTHER INCLUSIONS I04: Participant or participant and parent(s)/legally acceptable representative(s) are able to attend all scheduled visits and to comply with all study procedures. EXCLUSION CRITERIA Participants are not eligible for the study if any of the following criteria are met: MEDICAL CONDITIONS E01: Thrombocytopenia, presence of bleeding disorder, or receipt of anticoagulants in the 3 weeks preceding inclusion, contraindicating blood sampling, currently or previously suffering from any immune disorder. E02: Chronic illness that, in the opinion of the investigator, is at a stage where it might interfere with study conduct or completion. E03: Active nodulocystic acne, acne conglobata, acne fulminans, secondary acne (eg, chloracne, drug-induced acne) or o…