This thesis describes six studies which characterized tumor-infiltrating leukocytes (TIL) in colorectal cancer. TIL have shown to be of importance in the natural anti-tumor immunity of cancer patients. Chapter 1 gives an introductory overview of tumor immunology, TIL and colorectal cancer. In chapter 2 we describe the presence, location, and phenotype of tumor-infiltrating dendritic cells in colorectal cancer. With special attention to their association with other tumor-infiltrating immune cells, i.e. lymphocytes. Chapter 3 elaborates further on the role of tumor-infiltrating DC by evaluating whether there is an association between the presence and maturation status of tumor-infiltrating DC, T lymphocytes and clinical prognosis in patients with colorectal cancer. In chapter 4 NK cell infiltration in colorectal cancer is studied in relationship with loss of tumor MHC class I expression. In chapter 5 TIL were characterized in a case-control design, with tumors showing complete absence or normal expression of HLA class I. We further characterized TIL in a group of colorectal tumors displaying systemic P53 reactivity in chapter 6. Chapter 7 describes the technique of the multi-color immunohistochemical analysis, which we used to characterize the phenotype of TIL in the two preceding chapters. Chapter 8 Summary and Discussion.KWF KankerbestrijdingUBL - phd migration 201
