Modulation of dendritic cell function by leishmania parasites

The interactions between Leishmania parasites and dendritic cells (DCs) are complex and involve paradoxical functions that can stimulate or halt Tcell responses, leading to the control of infection or progression of disease. The magnitude and profile ofDC activation vary greatly, depending upon the Leishmania species/strains, developmental stages, DC subsets, serum opsonization, and exogenous DC stimuli involved in the study. In general, the uptake of Leishmania parasites alone can trigger relatively weak and transient DC activation; however, the in- tracellular parasites (amastigotes) are capable ofdown- modulating LPS/IFN-γ-stimulated DC activation via multiple mechanisms. This review will highlight current data regardingthe initial interaction ofDC subsets with invadingparasites, the alterations ofDC signalingpath- ways and function by amastigotes, and the impact of DC functions on protective immunity and disease pathogenesis. Available information provides insight into the mechanisms by which DCs discriminate between the types of pathogens and regulate appropriate immune responses.