The Role of CD4+T Cells in the Immune Response to Trypanosoma Cruzi in Mice Held at Elevated Environmental Temperature
The immune response of mice infected with Trypanosoma cruzi (the causative agent of Chagas' disease) has been extensively studied, and it has been demonstrated that changes in environmental temperature can influence the resistance of infected mice to the parasite. In particular, several investigators have demonstrated an increased resistance to T. cruzi infection when infected mice are maintained at 36°C. This increased resistance is reflected in decreased parasitemias and increased longevity. In addition, this enhanced resistance has been shown to be an immunological phenomenon. CD4+ T cells play a very important role in immune responses to parasitic infections through the secretion of cytokines. To explore a possible role for CD4+ T cells in this enhanced resistance to parasitic infection, anti-CD4 monoclonal antibody was used to deplete CD4+ T cells prior to infection. Parasitemia and mortality of mice were monitored under different environmental conditions. The results of this experiment indicate that 1) CD4+ T cells do play a role in this temperature related resistance to the parasite; 2) CD4+ T cells were particularly necessary early in infection for mice maintained at higher temperature to establish a protective resistance to T. cruzi\ 3) enhanced resistance to T. cruzi at elevated temperature also involves CD4+ T cell independent pathways; 4) Elevated temperature may have an enhancing effect upon the activity of CD4+ T cells.
Networked Digital Library of Theses and Dissertations