Induction of CD4⁺ and CD8⁺ T cell responses in efferent lymph responding to Toxoplasma gondii infection: analysis of phenotype and function

Abstract

The kinetics of induction of T cell responses were examined in efferent lymph from a node draining the site of a primary inoculation of Toxoplasma gondii. The numbers of T cells increased after infection, due initially to an expansion of the CD4+ T cell population followed by an increase in the number of CD8+ T cells which coincided with the peak lymphoblast response. Proliferative responses of CD4+ T cells to T. gondii antigen were detectable from day six after infection and immune efferent lymph cells inhibited the intracellular multiplication of T. gondii in vitro. Optimum inhibition was achieved using CD8+ T cells restimulated in vitro, and the effector function appeared to be directed preferentially against the autologous rather than the allogeneic infected target cell. The results provide unique information on the induction of immune responses to T. gondii in vivo and provide evidence that both CD4+ and CD8+ T cells are necessary for the development of protective immunity induced by the S48 strain of T. gondii which is used as a live vaccine in sheep.

Mice Lacking the Chemokine Receptor CCR1 Show Increased Susceptibility toToxoplasma gondiiInfection

“…The increased susceptibility of CCR1 Ϫ/Ϫ mice could not be attributed to an inadequate cellular immune response generated against the parasite. Cell-mediated immunity plays a critical role in protection against T. gondii infection (44). Both NK cells and T cells have an important function during murine toxoplasmosis (4,45).…”

Survival, immune responses and tissue cyst production in outbred (Swiss white) and inbred (CBA/Ca) strains of mice experimentally infected with Neospora caninum tachyzoites

“…In order to separate the parasites from the cell debris, the suspension was extruded trough a 27-G needle, centrifuged at 165 g, washed once in PBS and the parasites were counted in a Neubaeur chamber. For the preparation of the antigenic extract, tachyzoites were treated by three freeze-thawing cycles followed by sonication [9]. Protein concentration was measured by the BCA method, and then the antigenic solution was divided into aliquots and stored at -20 °C until further use.…”

Veterinary vaccines against Toxoplasma gondii

“…This early induction of IFNγ may be important in limiting intracellular multiplication of the parasite (Oura et al 1993) and may also help to create an appropriate cytokine microenvironment to induce a Th-1 type adaptive immune response (Gazzinelli et al 1996). A phenotypic analysis of the lymphoblast cells responding to a primary T. gondii infection in sheep showed an initial predominance of CD4+ T-cells (Innes et al 1995a). Around day 10 post-infection, when the peak lymphoblast response was observed, there was a switch to CD8+ T-cells being the dominant cell population.…”

“…Around day 10 post-infection, when the peak lymphoblast response was observed, there was a switch to CD8+ T-cells being the dominant cell population. In vitro studies showed that these activated CD8+ T-cells were able to inhibit intracellular multiplication of tachyzoites (Innes et al 1995a) and following the peak lymphoblast response in efferent lymph draining the site of infection the parasites were no longer detected within the lymph samples (Innes & Wastling 1995). Specific antibodies to T. gondii were detected from day 10-12 after the initial infection (Innes & Wastling 1995).…”

“…It is also unable to initiate the sexual life cycle in cats and cannot lead to the production of oocysts. The S48 strain tachyzoites are able to undergo limited multiplication within the sheep, and therefore induce protective cellmediated immune responses involving CD4+, CD8+ T-cells and IFNγ (Innes et al 1995a). In sheep vaccinated with S48 and then challenged with an additional live infection, the parasite is prevented from spreading within the lymph system (Buxton et al 1994).…”