Experimental American leishmaniasis in the Brazilian squirrel monkey (Saimiri sciureus): lesions, hematology, cellular, and humoral immune responses.

Unulcerated cutaneous lesions appeared and persisted in squirrel monkeys experimentally infected with Leishmania braziliensis braziliensis or L. b. panamensis. Peripheral blood mononuclear cell (PBMC) numbers increased following infection, and cultured PBMCs from infected monkeys proliferated in response to parasite antigens. The responses of PBMCs to mitogens were not suppressed in infected monkeys. Elevated levels of leishmania-specific immunoglobulins M and G were also observed. Thus, the squirrel monkey is susceptible to American leishmaniasis and is capable of responding to the infection with measurable cellular and humoral immunity.