Role of Langerhans cells and Thy. 1⁺ effector cells in herpes simplex virus-1 infection in the skin of newborn mice

Langerhans cells function in the epidermis as very potent accessory cells. Their role as antigen-presenting cells in the immune response following herpes simplex virus type 1 (HSV-1) skin infection of newborn mice was studied. Newborn C 57 BL/6 mice were found to be susceptible while adult mice are resistant to HSV-1 infection in the skin. Because the immune response to HSV-1 infection in the skin is mainly cell-mediated, and therefore dependent on the presence of functional accessory cells, the state of Langerhans cells in the skin of newborns was studied. Staining of whole epidermal mounts revealed similar numbers of Ia⁺ and ATPase⁺ Langerhans cells in the epidermis of newborn and adult mice. In a skin lymphocyte reaction assay, Langerhans cells derived from newborn mice were shown to stimulate proliferation of T cells derived from adult allogeneic mice to the same degree as adult-derived Langerhans cells. HSV-1 was injected into the skin of C 57 BL/6 newborn mice together with various preparations of adult-derived spleen cells devoid of antigen-presenting cells. The injected adult-derived lymphocytes were found to confer protection against HSV-1 infection in newborn mice, despite the lack of detectable antigen-presenting cell (APC) function in this cell preparation. The cell subset involved in the transfer of resistance was found to be Ia^- and Thy. 1⁺.