The Local T Cell Response in Experimental Leishmaniasis

Leishmania protozoa infect mononuclear phagocytes, replicate in parasitophorous vacuoles, and cause either visceral or cutaneous disease in a susceptible host. Inbred mouse strains provide useful experimental models in understanding the cell mediated immune response that controls susceptibility or resistance to leishmanial infection. Systematic analysis of T lymphocyte subsets have implicated the L3T4+ T cell in both protective and suppressive immunity in leishmania infection [1, 2]. We have chosen mouse strains that are acutely susceptible to infection but differ in their capacity to develop acquired resistance. These include BALB/c and C57BL/6 mice in L. mexicana amazonensis cutaneous infection, and athymic (nu/nu) and euthymic (+ / +, nu/+) BALB/c mice in L donovani visceral infection. We have analyzed the cell types that accumulate at the local site of infection, skin and liver, using immunocytochemistry. We provide evidence that failure to mount a local T cell response is associated with prolonged susceptibility in the Leishmania-infected animal.