Role of dendritic cells in the induction of TH1 and TH2 responses: implications for immunotherapy and pathology.

Description of projects available to graduate students:
Dendritic cells (DC) are the carriers of pathogen-related information within the immune system. DC provide T cells with Ag-specific “signal one”, and costimulatory “signal two”, acting as a source of information about molecular identity and potential pathogenicity of the invader. The combination of “signal one” and “signal two” allows immune system to mount the immune response of proper specificity and optimal magnitude.
In addition to the specificity and magnitude, a third element that determines the success of the immune response is its appropriate character or class. Cellular immunity and humoral immunity constitute two major classes of immune responses. Cell-mediated immunity, mediated by type-1 T helper (Th1) cells, cytotoxic T lymphocytes (CTL) and natural killer (NK) cells protects us from intracellular pathogens, including intracellular parasites, mycobacteria, and chronic intracellular phase of viruses, as well as against cancer. In contrast, it is poorly effective against the pathogens living outside the cells. Humoral immunity, mediated by Th2 cells, and B cell-produced antibodies, effectively fights extracellular bacteria and prevents the dissemination of viruses between our cells and tissues, but is ineffective against intracellular parasites and cancer.
A growing body of evidence indicates that migrating DC, carrying the pathogen-related signals one and two, also carry an additional “signal three” or “polarization”. This additional signal differentially drives immune responses towards Th1 or Th2 direction. Our current research analyzes how DC acquire such differential “signal three", focussing on the instructive (or helper) role of other types of immune cells, such as CTL, NK cells, and B cells, that till recently have been considered to be purely effector, rather than regulatory cell types.
Since DC are currently being used to induce therapeutic immune responses against cancer, we analyze the role of DC polarization in the induction of desirable Th1- and CTL-dominated anti-tumor immunity. This line of research aims at the development of optimized immunotherapeutic strategies for cancer patients. In addition, we investigate the role of the negative impact of tumors on DC in the ability of tumor to evade the immune system, searching for the ways to counteract tumor-induced immune dysfunction. The currently active projects include:

- CELLULAR INTERACTIONS AFFECTING DC POLARIZATION

- USE OF POLARIZED DC TO INDUCE THERAPEUTIC TH1 AND CTL RESPONSES AGAINST CANCER

- FUNCTIONAL MODULATION OF DC BY TUMOR ENVIRONMENT

Techniques graduate student will learn:
· Isolation of different populations of immune cells from peripheral blood and bone marrow (human, mouse)
· Cell culture techniques (generation of dendritic cells from blood and bone-marrow precursors; in vitro induction of primary responses of CD8 and CD4 T cells; generation of Ag-specific CD4+ T cell lines, Th1 and Th2 clones; generation of NK cells from bone marrow precursors)
· In vitro analysis of the interactions between different immune cell types (DC, CD8 T cells, CD4 T cells, NK cells, B cells, tumor cells)
· FACScan-based analysis of cell surface phenotype.
· Cytokine production tests: intracellular staining, ELISA, ELISPOT, RT-PCR.
· Antigen presentation assays.
· Radioactive and nonradiactive tests of cell activation and proliferation.
· Cytotoxicity assays.
· FACScan-based apoptosis assays