The role of chemokines and accessory cells in the immunoregulation of cutaneous leishmaniasis.

The course of infection with Leishmania parasites is determined by the type of the developing CD4+ T cell immune response. Macrophages and Langerhans cells/dendritic cells play a decisive role in the interaction between the parasites and the host's immune system because they serve as host cells, as accessory cells that present parasite antigen, deliver costimulatory signals and secrete cytokines modulating the T cell activity and as effector cells eliminating the microorganisms. Therefore, we put particular emphasis on characterizing the role of these cells in cutaneous leishmaniasis and the factors regulating their activities. Our results show that (1) expression of the chemokine monocyte chemoattractant protein 1 (MCP-1) is associated with macrophage infiltration into the lesion and stimulation of leishmanicidal activity, (2) Langerhans cells are required for the transport of Leishmania from the infected skin to the draining lymph node and initiation of the specific T cell immune response in the early phase of infection, (3) lymph node dendritic cells containing persistent parasites may be involved in the maintenance of specific immunity, (4) Langerhans cells are able to present L. major LPG to T cells and (5) treatment of mice with antigen-pulsed Langerhans cells induces protective immunity against cutaneous leishmaniasis.