Human T-Cell Clones as Tools to Identify Protective Antigens of Toxoplasma Gondii

Abstract

Many in vitro and in vivo observations indicate that cell-mediated immunity plays an essential role in protection of the host against toxoplasmosis. In the mouse experimental model, it has recently been shown that both CD4+ and CD8⁺ lymphocytes are important in controlling acute infection and preventing reactivation of chronic toxoplasmosis [Suzuki and Remington, 1988; Araujo, 1991; Gassinelli et al, 1991; Gazzinelli et al 1992]. The exact mechanism by which these T-cell subsets confer protection has not yet been fully elucidated, but two lymphokines (IL-2 and IFN-γ) produced by these T-cells have been demonstrated to have a protective activity [Sharma et al., 1985]; Suzuki et al., 1988; Suzuki and Remington, 1990; Suzuki et al. 1990; Gazzinelli et al., 1991]. Parasite-specific T-cell clones (TCC) derived from naturally infected and immune individuals offer an ingenious way to dissect the cell-mediated immune response and to identify the parasite antigens which induce protective effector mechanisms. Such antigens should thus be considered as subunit vaccine candidates.