Parameters of T Cell Activation in Murine Leishmaniasis

Abstract

Immunity to Leishmania has been shown in many studies to predominantly reflect the induction of specific cell mediated immune responses. Protective responses as generated in resistant mouse strains are accompanied by the generation of antigen specific T cell populations bearing the L3T4⁺ phenotypic marker and able to produce soluble mediators (lymphokines) capable of inducing normally quiescent macrophages to a state of leishmanicidal activity.¹ Recently, however, attention has also focussed on the possible role of Lyt2⁺ T cells.^2,3 The situation has been further complicated by the additional demonstration that there may be functional variability between T cells in vitro vs. in vivo. Thus, macrophage activating T cells clones can exacerbate disease in cell transfer experiments.⁴ In spite of the numerous studies on lymphocyte responses during Leishmania infection, many vital questions evidently remain unanswered.