Overview of Project

Regulatory T cells are required to prevent inflammatory and autoimmune disease, both in animal models and in humans. For example, our group has recently shown that patients with inflammatory bowel disease have abnormally low numbers of regulatory T cells. Despite their importance, we still don’t know exactly how they function in the body, and the proposed mechanisms based on in vitro studies are controversial. In particular, our laboratory has shown that regulatory T cells downregulate the expression of costimulatory molecules by dendritic cells, and thus prevent the normal repertoire of low affinity self-reactive T cells from becoming activated. However the in vitro assays do not measure this aspect of regulatory cell function, and the mediators that are implicated in in vitro function do not affect expression of costimulatory molecules in vivo.

Regulatory T cells are selected in the thymus after exposure to self antigen. We have a unique double transgenic model in which T cells expressing a transgenic T cell receptor contact their specific antigen expressed as a transgenic neo-self antigen. This generates a large population of regulatory T cells with the transgenic specificity, and allows us to harness the power of the transgenic approach to study this important cell population. The double transgenic model provides an ideal system for studying this how regulatory T cells function.

Project Outline

Using gene chip data obtained from the double transgenic model, we have already generated a list of candidate genes for molecules involved in regulatory T cell function. These genes are turned on when regulatory T cells recognise their antigen in vivo. The project will test which of these molecules is required for the suppressive function of regulatory T cells and which ones are used when regulatory T cells interact with dendritic cells. To study these molecules, we will first confirm their expression with quantitative PCR and/or Western blotting. We will then either generate regulatory T cells in gene knockout models (we already have double transgenic mice on CTLA-4 and IL-2 knockout backgrounds), or use monoclonal antibodies to block function.

Techniques: This project will give the student experience in lymphocyte purification and labelling, tissue culture, flow cytometry, DNA microarrays, bioinformatics, and RT-PCR.