M.S. California State Polytechnic University, Pomona, 1992
Ph.D. Oregon Health & Science University, Portland, OR, 2001
Work in my lab focuses on antigen recognition and activation of CD4+ T lymphocytes.
CD4+ T lymphocytes recognize antigenic peptide fragments presented on the surface of antigen presenting cells (APC) by major histocompatiblility complex (MHC) class II proteins. Triggering of the T cell antigen receptor (TCR) by binding to the MHC:peptide ligand induces dramatic morphological changes as the T cell flattens against the APC and increases contact area forming stable T-APC conjugates. This initial antigen recognition is followed by large-scale spatial and temporal molecular rearrangements of plasma membrane proteins and intracellular signaling molecules. These rearrangements lead to the formation of an ordered structure at the T-APC interface termed the immunological synapse. The synapse is involved in T cell signaling as well as the site for delivery of T cell effector functions. We have previously shown that molecules from the APC are transferred to the T cell across the immune synapse in a process called trogocytosis.
Work in our lab focuses on two important areas related to T lymphocyte biology:
• The impact of the herbicide Atrazine on the activation of CD4+ T cells and the mechanism underlying a significant increase in Foxp3+ regulatory T cells;
• The biological consequences on individual T cells after the capture of APC membrane fragments from T-APC immunological synapse, a process termed “trogocytosis”
We are examining the biological significance of intercellular transfer of molecules from APC to T cells (termed trogocytosis). We have previously shown that upon dissociation from APC, T cells capture MHC:peptide molecules from the immunological synapse and imaging data suggests that these molecules continue to signal to the T cell. Our 2012 paper suggests that these trogocytosed molecules sustain intracellular signaling, which leads to selective survival of the trogocytosis positive cells, in vitro. Our working hypothesis is that this controls an ongoing immune response by continuous cell autonomous signaling and by intercellular interactions in T cell – T cell antigen presentation. This T-T presentation may potentiate an immune response and/or may play an important role in peripheral tolerance, as antigen presentation by T cells results in anergy induction in vivo in some experimental systems.
Immunotoxicology of Atrazine
We are examining the impact on Atrazine on thethe activation and differentiation of CD4+ T cells. Atrazine is a very widely applied herbicide that the USGS estimates contaminates 70% of the ground water in the US. It has been linked to birth defects, cancer, immune developmental defects and modulation of immune cell effector functions. We have shown that Atrazine inhibits lymphocyte proliferation and lymphocyte effector function. In addition, we have shown that the frequency of Foxp3 positive regulatory T cells doubles in atrazine-treated cultures. We have recently found that male and female T cells repsonde differently to atrazine exposure. We are now examining the impact of Atrazine-induced elevated es
American Association of Immunologists
University of Montana Center for Environmental Health Sciences
Scientific Director, University of Montana Molecular Histology and Fluorescence Imaging Core Facility
UM Interdepartmental Immunology Graduate Degree Track
UM DBS Integrated Microbiology and Biochemistry Graduate Program