The Role of Dendritic Cells at the Early Stages of Leishmania Infection

Abstract

6. CONCLUSIONExperimental infection of mice with L. major provides a valuable model to analyze the immunoregulatory events that modulate the course of infection with intracellular micro-organisms. In particular, the study of the functions of dendritic cells in murine cutaneous leishmaniasis revealed that these cells have a pivotal role in the initiation, regulation and maintenance of immune responses to infection. The recent finding that dendritic cells can serve as vehicles for vaccination against leishmaniasis indicates that the cells elicit efficient and long-lasting immunity, mimicking the response induced by natural infection. In this context, many features of dendritic cells need to be understood in more detail to allow their use for immunoprophylactic or therapeutic intervention. The molecular mechanisms underlying the processing of parasite antigens by dendritic cells and the loading onto MHC molecules or other restriction elements, such as the CD1 molecule, are largely undefined. The latter aspect is particularly relevant as CD1 molecules have been shown to present lipoglycan antigens to specific T cells (Porcelli and Modlin 1999) and this type of antigen is highly abundant on the surface of Leishmania parasites and other infectious agents. It is also not known whether parasites or parasite products interfere with dendritic cell activation or deviate dendritic cell functions in order to escape the immune response. Further studies will contribute to a better understanding of these issues.