Lymphocyte-mediated immune responses to Leishmania infection.

Leishmania are intracellular protozoan parasites transmitted to humans by the bite of infected phlebotomine sand flies. Human infection is often asymptomatic but can develop into a broad spectrum of clinical diseases, collectively termed the leishmaniases. The underlying immunological features associated with asymptomatic infection and the varying clinical forms of disease have been extensively studied in pre-clinical models (including rodents, dogs and primates), as well as in human populations. Here, concentrating on data derived from human studies, we review the current understanding of how diverse lymphocyte-mediated immune responses drive the human disease spectrum seen following Leishmania infection.