..... ................................................................................................................................. iii Özet ............ .................................................................................................................................. v Acknowledgements .................................................................................................................... viii Table of contents ........................................................................................................................... x List of figures .............................................................................................................................. xv List of tables .............................................................................................................................. xix Abbreviations .............................................................................................................................. xx Chapter 1 .... Introduction ............................................................................................................... 1 1.1 The Immune System ......................................................................................................... 1 1.2 Myeloid Cells .................................................................................................................... 2 1.2.1 Monocytes ............................................................................................................. 2 1.2.2 Macrophages ......................................................................................................... 3 1.2.2.1 M1 Macrophages .................................................................................................. 3 1.2.2.2 M2 Macrophages .................................................................................................. 6 1.2.2.3 Macrophages Generated by M-CSF and GM-CSF ............................................... 9 1.2.2.4 Tumor-associated Macrophages ......................................................................... 10 1.2.3 Myeloid Derived Suppressor Cells ..................................................................... 12 1.2.3.1 MDSC under disease conditions ......................................................................... 13 1.2.3.2 MDSC-Mediated Immune Suppression .............................................................. 14 1.2.3.3 Response of MDSC to Soluble Factors............................................................... 16 1.2.3.4 Therapeutic strategies for MDSC targeting ........................................................ 19 1.2.3.4.1 Response of MDSC to TLR Agonists ....................................................... 22 1.3 Extracellular Vesicles ..................................................................................................... 25 1.3.1 Therapeutic Potential of EV ................................................................................ 26