Supplementary Material for: Is Human Sebum the Source of Skin Follicular Ultraviolet-Induced Red Fluorescence? A Cellular to Histological Study

<b><i>Background:</i></b> The ultraviolet-induced red fluorescence (UVRF) from human skin follicles was suggested to be a result of <i>Propionibacterium acnes</i> and was used for the monitoring of acne. More recent studies suggested that the UVRF may be more related to sebum rather than to microorganisms. <b><i>Objective:</i></b> To clarify whether human sebum or follicular microorganisms are the source of UVRF. <b><i>Methods:</i></b> We examined the fluorescence of human-derived SZ95 sebocytes, human sebaceous glands, sebum extracted from the sebaceous glands, and bacteria isolated from human hair follicles under ultraviolet light. <b><i>Results:</i></b> SZ95 sebocytes, human sebaceous glands, and sebum do not emit UVRF. Two types of UVRF peaking at about 635 nm and at about 620 nm were detected in <i>P. acnes</i> and <i>Staphylococcus epidermidis</i>, respectively. This is the first report that <i>S. epidermidis</i> emits UVRF when it is anaerobically cultured and then exposed to air. <b><i>Conclusion:</i></b> Human follicular UVRF is emitted by resident bacteria, not by sebum. Therefore, UVRF may be used to monitor certain species of skin microorganisms.