Which cells present antigen to CD4 T cells in vivo?
Supervisor:
Senior
Research Officer
T
Cell Biology Group (group head, A/Prof B.Fazekas de St.Groth)
Centenary
Email: e.shklovskaya@centenary.usyd.edu.au
Phone
9565 6198
This work is a
continuation of two current projects in our laboratory. One of them deals with
presentation of antigen to CD4 T cells by epidermal-derived dendritic
cells. The other project looks at the phenomenon whereby MHC class II molecules
with antigen bound to them are transferred from one dendritic
cell to another. We deal with true biological phenomena as they happen in vivo.
Why dendritic
cells?
Dendritic cells (DCs) represent a unique subset of antigen-presenting cells
that are involved in capture of foreign antigens in the peripheral tissues and
subsequent processing of these antigens into peptides that can be recognised by
rare antigen-specific T cells. After antigen recognition, T cells proliferate
and differentiate into effector T cells that are
involved in antigen clearance, and memory T cells that form long-term
immunological memory. The potential of DCs to
activate T cells is superior to all other types of antigen-resenting cells.
Why CD4 T cells?
They are the ultimate controllers of the
immune system. CD4 T cells are required for long lasting CD8 T cell memory.
More importantly they provide the “brakes” when the immune response turns
against “self” (autoimmunity).
What is the project about?
A bone marrow chimeric
mouse was recently developed in our laboratory in which only epidermal-derived DCs express MHC class II-IE molecules and therefore can
present a model antigen (MCC) to antigen-specific CD4 T cells. In our readout
system, CD4 T cells express a transgenic T cell receptor specific for MCC bound
to IE. We have characterized IE chimeric mice in
detail, including looking at all DC subpopulations. We have also studied T cell
responses in these mice and we know that T cells respond differently in our
chimera compared to a mouse where all DCs express IE.
What we don’t know yet is the potential role that transfer of MHCII-IE:MCC complexes from epidermal DCs
to other DCs in the lymph node may play in tuning an
ongoing CD4 T cell response. The process of antigen-MHC transfer between the dendritic cells is a recently described phenomenon and a
“hot topic” at the moment.
Mouse in vivo
techniques (including various ways of vaccination and intravenous injections,
isolation of mouse lymph nodes and spleens, labelling of cell suspensions with
CFSE dye and T cell adoptive transfer)
Flow cytometry 7-9
colour – remember, we have the best Flow facility in
FACS sorting
In vitro assays (T cell
proliferation, cytokine re-stimulation)
Monoclonal
antibody purification