Abstract. The aim of this study was the identification of surrogate markers of host immunity in renal cell carcinoma (RCC) patients. Using 4-color flow cytometry the immunophenotype of blood immune cells of RCC patients was compared to that of healthy volunteers and correlated with staging and grading of patients. Furthermore, the time course of these immune markers was compared in RCC patients undergoing either open surgery or laparoscopy. Compared to the healthy control group, blood of RCC patients contained more granulocytes and higher percentages of CTLA4 + cD8 + T lymphocytes, but reduced numbers of dendritic cells (DCs) and of CD28 + cD8 + T cells. Tumor progression was associated with a higher white blood cell count, a reduced frequency of blood DCs and increased numbers of CD57 + T and NK cells. Monocytes of patients with advanced RCC showed a reduced HLA-DR surface expression associated with higher aminopeptidase N(APN)/CD13 expression. Tumor surgery caused an increase of granulocytes and a decrease of all lymphocytic and DC subpopulations within 24 h, whereas the number of HLA-DR low monocytes was up-regulated. As demonstrated by time kinetic analysis, laparoscopic intervention caused a more moderate immunosuppression and an enhanced restoration of immune activity than open surgery. These results suggest that the composition and the phenotype of innate immune cells reflect well the differences in the cellular immunity of RCC patients associated with tumor disease as well as surgery. The monocytic HLA-DR intensity represents a suitable marker for monitoring tumor stage and surgery-associated immunosuppression in RCC patients.

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