Herpes simplex virus type 1 pathogenicity in footpad and ear skin of mice depends on Langerhans cell density, mouse genetics, and virus strain.

Skin Langerhans cells have been shown to be very efficient in presenting antigens to T-helper cells and stimulating the immune response. The present study demonstrates their essential role in the control of primary herpetic infections in the skin. Two unrelated stimuli (abrasion and steroids) were shown to cause depletion of the Langerhans cells in the murine epidermis, and both caused enhancement of the virulence of herpes simplex type 1 (HSV-1) in the skin. The Langerhans cell density was found to be lower in the skin of the ear than in the footpad. HSV-1 was consistently more virulent when injected into the ear epidermis than in the footpad. Thus, HSV-1 pathogenicity in mouse skin depends on the mouse age and strain, the virus strain, and the state of the epidermal Langerhans cells. These findings are discussed in relation to the antigen-presenting cell function of the Langerhans cells.