title: Myeloid-derived suppressor cells in human peripheral blood: Optimized quantification in healthy donors and patients with metastatic renal cell carcinoma.
abstract: Induction of myeloid-derived suppressor cells is an important mechanism leading to tolerance against tumors. Phenotypic characterization of MDSC has been established and heterogeneous populations with monocytic or granulocytic features have been characterized. Increased levels of MDSC have been described in metastatic renal cell carcinoma and seem to correlate with an adverse outcome. As MDSC constitute only small populations in peripheral blood of cancer patients, it is highly important to achieve technically optimized conditions for quantification. Different cell preparation techniques--besides freezing and thawing--are potential sources of substantial variation. Our study was focused on an optimized quantification of MDSC in pB of healthy donors and patients with mRCC, in whom major technical sources of variation were analyzed. Whole blood and peripheral blood mononuclear cells were used for the flow cytometric quantification of MDSC in the pB of mRCC patients and healthy donors. We compared (1) analysis in whole blood vs. PBMC after Ficoll gradient centrifugation and (2) immediate analysis after blood drawing vs. analysis one day later. Finally, in order to evaluate our optimized technical approach, pB of 15 patients with histologically confirmed mRCC under treatment with either sunitinib or sorafenib was analyzed. No difference in the number of MDSC was observed after analysis in whole blood vs. PBMC. In contrast, the time point of analysis was a source of substantial variation (one day later vs. immediate analysis after blood drawing). In conclusion, for optimal analysis of MDSC, immediate analysis of whole blood after blood drawing rather than one day later seems to be most appropriate under the aspect of practical feasibility and reliability. Using this method, we were able to confirm both (a) increased numbers of MDSC in patients with mRCC and (b) a decrease of MDSC under sunitinib therapy.
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine, Campus-Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Sylter Str. 2, 13353 Berlin, Germany. Electronic address: anne.floercken@charite.de.
authors.forename: Anne
authors.initials: A
authors.lastname: Flörcken
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine, Campus-Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Sylter Str. 2, 13353 Berlin, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Takvorian
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine, Campus-Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Sylter Str. 2, 13353 Berlin, Germany.
authors.forename: Anju
authors.initials: A
authors.lastname: Singh
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine, Campus-Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Sylter Str. 2, 13353 Berlin, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Gerhardt
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine, Campus-Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Sylter Str. 2, 13353 Berlin, Germany.
authors.forename: Benjamin Nils
authors.initials: BN
authors.lastname: Ostendorf
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine, Campus-Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Sylter Str. 2, 13353 Berlin, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Dörken
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pezzutto
authors.affiliation: Department of Hematology, Oncology, and Tumor Immunology, Charité-University Medicine, Campus-Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany; Labor Berlin Charité Vivantes GmbH, Sylter Str. 2, 13353 Berlin, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Westermann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001782:Blood Donors; D001800:Blood Specimen Collection / Q000379:methods; D002292:Carcinoma, Renal Cell / Q000097:blood* / Q000473:pathology; D005240:Feasibility Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007680:Kidney Neoplasms / Q000097:blood* / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D022423:Myeloid Cells / Q000378:metabolism*; D009362:Neoplasm Metastasis; D015203:Reproducibility of Results; D013997:Time Factors
keywords: Flow cytometry; Myeloid-derived suppressor cells; Renal cell carcinoma