QUANTITATIVE DIFFERENCES IN CELL-SURFACE EXPRESSION OF CLASS-I MHC ANTIGENS ON MURINE EPIDERMAL LANGERHANS CELLS

Epidermal Langerhans cells are derived from cells of bone marrow origi n and, as the primary APC population in the skin, are responsible for initiation of many immune responses. Consequently, cell surface expres sion of MHC Ags by Langerhans cells is central to their function. Alth ough murine Langerhans cells express class II MHC Ags at high levels, their level of expression of class I MHC has been controversial. In th is study, cell surface expression of multiple individual class I MHC A gs on murine epidermal Langerhans cells was analyzed using quantitativ e immunofluorescence. It was found that Langerhans cells differentiall y express products of distinct class I genes. Langerhans cells express ed low cell surface amounts of H-2K and Qa-2, whereas expression of su rface H-2D and H-2L by the same cells was high. Murine epidermal Lange rhans cells therefore express low cell surface amounts of some but not all class I MHC Ags. Differential surface expression of products of d istinct class I MHC genes by Langerhans cells may have a profound effe ct on cutaneous immune responses.