Role of phagocytic macrophages in induction of XXXX and tolerance by hapten applied to normal and ultraviolet B-irradiated skin.

@entity19 @entity18581 @entity19160 @entity56
Liposomes containing the drug @entity19160 ( @entity19160 ) can eliminate phagocytic cells, such as macrophages, when injected in vivo. In this paper we report that @entity19160 -containing liposomes have been used experimentally to determine the extent to which cutaneous macrophages participate (1) in the induction of @entity56 ( @entity56 ) when hapten is painted on normal @entity19 skin, and (2) in the induction of @entity56 or tolerance when hapten is painted on @entity19 skin that has been exposed to ultraviolet B (UVB) radiation. Intradermal (i.d.) injections of @entity19160 -containing liposomes were found to have no deleterious effects on @entity56 induction via normal skin, whether the amount of hapten ( @entity18581 ) applied to the cutaneous surface was optimal or excessive. Moreover, @entity19160 -containing liposomes did not deplete the epidermis of Langerhans' cells. However, similar i.d. injections of @entity19160 -containing liposomes did prevent the induction of @entity56 when hapten was painted on UVB-irradiated skin of BALB/c @entity19 , a strain that develops @entity56 when hapten is applied to UVB-exposed skin. These findings indicate that the antigen-presenting cell (APC) function found in skin of UVB-resistant @entity19 following exposure to UVB radiation can be attributed to macrophages. This explains why these @entity19 develop and display @entity56 after UVB radiation. By contrast, i.d. injections of @entity19160 -containing liposomes failed to prevent the induction of the tolerance when hapten was applied to the surface of UVB-exposed skin of UVB-susceptible @entity19 , such as C57BL/6. Since the dermis of UVB-exposed skin of these @entity19 is known to contain a novel population of cells that can provide a tolerance-conferring signal, the current findings rule out macrophages as the responsible cell type.
