New Zealand black mice are immunologically resistant to high‐dose, but not low‐dose Leishmania mexicana infection

Abstract

The course of infection following s.c. inoculation of a wide dose range of L. mexicana stationary‐phase promastigotes (SPP) was examined in sexually mature and immature NZB mice of both sexes. Infection with a high dose (> 107 SPP) was able to induce a protective in vivo response, which could be adoptively transferred with parasite‐immune T cells, into naive, syngeneic recipients. In contrast, s.c. infection with a low dose (< 107 SPP) induced non‐healing lesions; disease susceptibility could also be transferred into naive animals with T cells from non‐immune donors. When the ability to mount a delayed‐type hypersensitivity (DTH) reaction was tested in these two groups, the high‐parasite dose group gave a significantly higher response. The in vivo protection and high DTH response were reflected in the ability of cells derived from the high‐dose resistant (but not low‐dose susceptible) mice to mount an antigen‐specific T cell response in vitro. The possible immunological effector mechanisms underlying high‐dose resistance and low‐dose susceptibility are discussed. Copyright © 1991, Wiley Blackwell. All rights reserved