Accumulating evidence indicates that myeloid cells are critically involved in the pathophysiology of human cancers. In contrast to the well-characterized tumor-associated macrophages, the significance of granulocytes in cancer has only recently begun to emerge. A number of studies found increased numbers of neutrophil granulocytes and granulocytic myeloid-derived suppressor cells (GrMDSCs) both in the peripheral blood and in the tumor tissues of patients with different types of cancer. Most importantly, granulocytes have been linked to poor clinical outcome in cancer patients which suggests that these cells might have important tumor-promoting effects. In this review, we will address in detail the following major topics: (1) neutrophils and GrMDSCs in the peripheral blood of cancer patients-phenotype and functional changes; (2) neutrophils and GrMDSCs in the tumor tissue-potential mechanisms of tumor progression and (3) relevance of neutrophils and GrMDSCs for the clinical outcome of cancer patients. Furthermore, we will discuss the advantages and disadvantages of the current strategies used for identification and monitoring of human MDSCs. We propose a six-color immunophenotyping protocol that discriminates between monocytic MDSCs (MoMDSCs), two subsets of GrMDSCs and two subsets of immature myeloid cells in human cancer patients, thus, allowing for an improved characterization and understanding of these multifaceted cells.

In tumor-bearing mice, immunosuppressive granulocytic and monocytic MDSC have been identified. The identity and function of MDSC in cancer patients are less clear and need further characterization. We analyzed the peripheral blood of 103 patients with HNC, lung cancer, or cancers of bladder and ureter. Based on sedimentation properties in density gradients, a subset of LD-PMN was identified and analyzed. LD-PMN were expanded in the peripheral blood of cancer patients, suppressed proliferation, and IFN-γ production of polyclonally stimulated T cells and thus, qualify as human MDSC. Immunophenotyping and morphological analysis revealed the accumulation of immature PMN in the MDSC fraction. Neutrophilic MDSC showed altered surface marker expression, prolonged survival, and impaired effector functions when compared with conventional, mature PMN of regular density. MDSC displayed markedly reduced chemotaxis toward tumor-conditioned medium and lacked expression of chemokine receptors CXCR1 and CXCR2, which are normally required for PMN extravasation from the bloodstream and subsequent tissue infiltration. Collectively, our data suggest the accumulation and persistence of long-lived, immature granulocytic MDSC with T cell-suppressive function and impaired migratory properties in the peripheral blood of cancer patients.

The progression of epithelial cancer is associated with an intense immunological interaction between the tumor cells and immune cells of the host. However, little is known about the interaction between tumor cells and polymorphonuclear granulocytes (PMNs) in patients with head and neck squamous cell carcinoma (HNSCC). In our study, we investigated systemic PMN-related alterations in HNSCC, the role of tumor-infiltrating PMNs and their modulation by the tumor microenvironment.We assessed the infiltration of HNSCC tissue by PMNs (retrospectively) and systemic PMN-related alterations in blood values (prospectively) in HNSCC patients (n 5 99 and 114, respectively) and control subjects (n 5 41). PMN recruitment, apoptosis and inflammatory activity were investigated in an in vitro system of peripheral blood PMNs and a human HNSCC cell line (FaDu). HNSCC tissue exhibited considerable infiltration by PMNs, and strong infiltration was associated with poorer survival in advanced disease. PMN count, neutrophil-to-lymphocyte ratio and serum concentrations of CXCL8 (interleukin-8), CCL4 (MIP-1b) and CCL5 (RANTES) were significantly higher in the peripheral blood of HNSCC patients than in that of controls. In vitro, HNSCC-conditioned medium inhibited apoptosis of PMNs, increased chemokinesis and chemotaxis of PMNs, induced release of lactoferrin and matrix metalloproteinase 9 by PMNs and enhanced the secretion of CCL4 by PMN. Our findings demonstrate alterations in PMN biology in HNSCC patients. In vitro, tumor-derived factors modulate cellular functions of PMNs and increase their inflammatory activity. Thus, the interaction between HNSCC and PMNs may contribute to host-mediated changes in the tumor microenvironment.Worldwide, head and neck cancer is one of the six most common cancers. More than 90% of head and neck cancers are squamous cell carcinomas (HNSCCs) that primarily originate in the oral cavity, the pharynx and the larynx. [1][2][3] HNSCCs display an inflammatory microenvironment with frequent infiltration by large numbers of immune cells. This infiltration results in a reciprocal interaction between the malignant tissue and the immune cells that causes local and systemic alterations, often resulting in the downregulation of immune functions and the tumor escape from immune control. [4][5][6] Accumulating evidence suggests that polymorphonuclear granulocytes (PMNs) and other myeloid cells play an important tumor-promoting role during tumor progression. 7-9 High numbers of PMNs before treatment, as determined in the peripheral blood of patients with malignant melanoma, 10 and an increased neutrophil-to-lymphocyte ratio (NLR), as demonstrated in ovarian cancer, 11 have been proposed as independent prognostic factors for short overall survival. Tumor-infiltrating PMNs have been linked to a poorer prognosis for patients with lung adenocarcinoma of the bronchioloalveolar subtype, 12 but they seem to be associated with a reduced mortality for patients with gastric carcinoma. 13 PMN functions are modulated by a variety of ...

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine that has been reported to enhance the aggressiveness and metastatic potential of tumor cells. However, the mechanisms through which MIF influences tumor development and progression are not understood. The objectives of our study were to assess the effects of tumor-derived MIF on neutrophils in head and neck cancer (HNC) and to identify possible feedback effects on tumor cells. To this end, we used an in vitro system to model the interaction between human HNC cells and neutrophils. In addition, we analyzed expression of MIF in tissues from HNC patients in relation to neutrophilic infiltration and clinical parameters. Our results show that human HNC is infiltrated by neutrophils proportional to the levels of tumoral MIF. Strong MIF expression by the tumor is associated with higher lymph node metastasis and reduced survival in HNC patients. In vitro, MIF modulated functions of human neutrophils by inducing chemokine CXC motif receptor 2(CXCR2)-dependent chemotaxis, enhancing neutrophil survival and promoting release of chemokine C-C Motif Ligand 4 (CCL4) and matrix metalloprotease 9(MMP9). Further, neutrophils activated with tumor-derived MIF enhanced migratory properties of HNC cells. In conclusion, our data indicate that the effects of tumor-derived MIF on neutrophils represent an additional mechanism by which MIF might contribute to tumor progression.

Solid tumors such as head and neck squamous cell carcinoma (UNSee) display an intense interaction between tumoral factors and the immune system. Functional modulation of tumor-infiltrating and peripheral blood immune cells plays an important role during tumor progression. In this pilot study we compared biological functions of polymorphonuclear granulocytes (PMN) from the peripheral blood of UNSee patients and healthy subjects. PMN were simultaneously isolated from the peripheral blood of UNSee patients and healthy donors for functional analysis (apoptosis, production of reactive oxygen species (ROS), cytokine release and immunophenotyping). PMN from UNSee patients showed a significantly lower inducible production of ROS (P = 0.02) and reduced spontaneous apoptosis (P = 0.008) compared with PMN from healthy donors. Under standard culture conditions, there was no significant difference regarding the release of inflammatory cytokines between PMN from UNSee patients and PMN from healthy donors. Confirming previous observations, serum concentrations of PMN-related cytokines were significantly higher in the peripheral blood of UNSee patients than in that of controls. Importantly, immunophenotyping revealed an increased number of immature PMN in PMN fractions isolated from UNSee patients. Peripheral blood PMN from UNSee patients and healthy donors show distinct functional differences. The presence of increased numbers of immature stages of PMN in UNSee patients may partly contribute to the changes observed. After recruitment to and infiltration of the tumor, PMN may be further modulated in the local tumor microenvironment. This pilot study justifies functional analyses of myeloid cells in larger cohorts of patients with UNSee.Cancer-related inflammation in solid tumors is associated with modulation of immune cells finally resulting in tumor progression (I). Head and neck squamous cell carcinoma (HNSCC) displays frequent infiltration by various immune effector cells and reciprocal interaction between tumor and immune cells. This interaction leads to an increased local and systemic expression of immune-modulating mediators, often resulting in immuno-suppression and the escape of the tumor from immune control (2). Accumulating evidence suggests that polymorphonuclear granulocytes (PMN, neutrophils) and other myeloid cells play an important tumor-promoting role during tumor progression (3-4). In the tumor host, tumor-derived factors modulate PMN functions: For instance, in bronchioalveolar carcinoma, production of antiapoptotic factors by the tumor