The Teyton Laboratory

Research Focus

T Cell Receptor Activation

Our goal is to understand the molecular switches that govern the initiation of T cell activation. Assembly of functional TCR complexes on artificial bilayers with recombinant forms of the TCRαβ, CD3δε, CD3γε and CD8αβ molecules has been accomplished. Single molecule, multicolor imaging by TRIFF microscopy (collaboration with Dr.D.Millar, TSRI) and electron microscopy are combined to appreciate the dynamics and membrane relationships of each subunit within the complex. Similar observations are carried out in the presence of MHC ligands displayed in solution or at the surface of polystyrene beads and liposomes to understand the dynamic relationships between the different constituents of the TCR complex. Interactions of MHC and TCR molecules with their respective membranes and their neighboring molecules could provide simple switches essential to T cell activation. This hypothesis is supported by our structure determination of an MHC molecule attached to a phospholipids bilayer that shows parallel orientation of the long axis of the molecule with the lipid leaflet (collaboration with Dr. Mitra, U.Auckland, NZ). Efforts to determine 3-dimensional structures of CD3, TCR complexes and CD8 αβ are pursued in collaboration with Dr. I.A.Wilson (TSRI).

Autoimmune Diabetes

MHC multimers are used to detect antigen-specific T cell populations in diabetes-prone NOD mice. The characterization of pathogenic T cells is done by single cell analysis of cytokine secretion and TCR usage. In vivo antigen-specific T cell removal is attempted as a therapy of IDDM by delivering MHC-bearing doxorubicin liposomes in the pre-clinical phase of diabetes. The specificity of the intervention will limit side effects and complications of general immunosuppression. The structure determination of the first TCR/diabetogenic MHC molecule complex has been completed and allows us to establish the first comprehensive hypothesis linking the single β57 MHC class II polymoprhism to immune diabetes. The same observations have now been expanded to human autoimmunity and HLA-DQ8 in collaboration with Dr. B. Jabri (U. of Chicago). These structural studies are the building blocks to designing new therapeutic targeting directly the MHC molecule.

CD4⁺ T Cell Repertoire Studies in Vaccination

The critical role of CD4⁺ T cells in shaping CD8 and B cell responses has been long recognized. However, following antigen-specific CD4⁺ T cells during infections or vaccinations has proven very challenging. A new generation of MHC class 2 tetramers has been produced in the laboratory and is now used to measure the breadth and diversity of CD4 T cells in Flu and Listeria infections. These studies are aimed at defining new vaccination procedures and strategies.

Link Innate/Adaptive Immunity: CD1-restricted Immunity

Lipid binding to CD1 is studied biophysically in order to determine the parameters that govern the presentation of these antigens to T cells. A family of lipid transfer proteins (LTP), known as saposins and belonging to the catabolic lipid pathway, has been shown to be critical for the loading of natural glycolipids onto CD1 and the selection of NK T cells. It appears that other LTPs such as Niemman-Pick C1 and C2 molecules or GM2 activator protein are also involved in the loading of endogenous and exogenous ligands. A large systematic study of CD1 within the context of lipid metabolism is under way in collaboration with Dr.Bendelac (U. Chicago) and Dr.Savage (BYU) using RNA interference, gene knock out and recombinant biochemistry. At a structural level our efforts are aimed at understanding the recognition of very dissimilar ceramides such as α-galactosyl ceramide and isoglobotrihexosyl ceramide (β-linked) by a T cell receptor bearing a unique α chain (Vα14 in mouse, Vα24 in human) and a limited set of Vβ partners. Natural and synthetic ligands for NKT cells are also investigated for their adjuvant properties in order to develop new vaccination approaches.

Innate Immune receptors: from Fly to Human

The recognition of unique features of the prokaryote world is embedded in the nature of a series of receptors of the innate immune system called pattern recognition molecules. Each of these receptors can sense the presence of family of unique prokaryotic compounds such as glycolipids, proteoglycans, and DNA/RNA molecules. We are involved in a large collaborative effort under the guidance of Dr.Ulevitch (TSRI) to decipher the signaling pathways operating in controlling innate immunity under normal physiological conditions and in diseases. Recombinant forms of receptor family members from Drosophila, mouse and human are expressed and use to produce unique reagents usable to delineate new activation pathways.