Thesis (MSc)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

T-cells are present in the immune system to fight against invaders. Once their job is done, suppressing their activity is an important step in maintaining a proper immune response. Myeloid derived suppressor cells (MDSCs) are immune cells that suppress T-cell activity. Currently, MDSCs are defined as a heterogeneous population of immature cells that are derived in the bone marrow and travel to the site of inflammation or cancer. Two major subtypes of MDSCs have been identified in mice and humans, monocyte-like MDSCs (M-MDSC) and granulocyte MDSCs (G-MDSC). G-MDSCs typically make up the majority of the total population of MDSCs but are less T-cell suppressive than M-MDSCs. One of the major problems in the study of MDSCs is that the current marker system for subtypes does not differentiate between precursor MDSCs (lacking suppressive ability) and functional MDSCs (those with suppressive ability). Therefore, using cancer models in mice, we investigated the development and potential to classify precursor MDSCs from functional MDSCs. While MDSCs have been highlighted as a target cell to inhibit in cancer, in other conditions, such as pregnancy, MDSCs have been shown to be beneficial in maintaining a normal pregnancy. Therefore, targeting the increase of MDSCs in abnormal pregnancy conditions like pre-eclampsia may act as a prevention or therapeutic strategy. Finally, it is known that many dietary components can act as modulators of immune cells. Specifically, the polyphenol like phytochemical, curcumin has been shown to act as an anti-inflammatory agent with the potential to modulate multiple immune cells. Therefore, we propose two different studies to investigate the potential of curcumin as either an inhibitor and/or promotor of MDSCs in a disease-specific context. Together the role of phytochemicals as immunomodulators of MDSCs is still very young, in part due to the complexity of phytochemicals themselves, but the studies cited here provide evidence that the field is ripe for additional questions to be asked.