In a prospective study, we have examined the tumor-specific immune response in a group of 59 patients with human papillomavirus (HPV) 16-positive (HPV16 + )-induced or HPV18 + -induced cervical cancer. Local antitumor immunity was analyzed by the enumeration of tumor-infiltrating dendritic cells and CD4 + , CD8 + , and regulatory T cells as well as by calculation of the ratio of CD8 + /CD4 + T cells and CD8 + / regulatory T cells. Systemic tumor-specific immunity was assessed by determination of the HPV E6-and/or E7-specific T-cell response in the blood of these patients. Finally, these variables were evaluated with respect to known histopathologic prognostic variables, including the absence (LN À ) or presence (LN + ) of lymph node metastases. Stratification according to the lymph node status of patients revealed a significantly stronger CD8 + T-cell tumor infiltration, a higher CD8 + /CD4 + T-cell ratio, and higher CD8 + /regulatory T-cell ratio in the group of patients in which the tumor failed to metastasize to the tumor-draining lymph node. Subdivision according to the presence (IR + ) or absence (IR À

Because of their important role in the maintenance of selftolerance, CD4 ؉ regulatory T cells prevent autoimmune diseases but also curtail the efficacy of T cell immune responses against cancers. We now show that this suppressive action of CD4 ؉ regulatory T cells is not limited to cancers displaying tumorassociated self antigens, such as melanomas, but also extends to human papillomavirus (HPV)-positive cervical cancers that express foreign tumor antigens. HPV-specific CD4 ؉ T cells isolated from lymph node biopsies of cervical cancer patients were found to suppress proliferation and cytokine (IFN-␥, IL-2) production by responder T cells. The capacity of HPV-specific CD4 ؉ T cells to exert this suppressive effect depended on their activation by cognate HPV antigen and on close-range interactions with responder T cells. HPV-specific CD4 ؉ regulatory T cells were also retrieved from cervical cancer biopsies, suggesting that they interfere with the anti-tumor immune response at both the induction and effector levels. Our findings offer a plausible explanation for the observed failure of the tumor-specific immune response in patients with cervical carcinoma.suppression ͉ Treg ͉ vaccine ͉ immunotherapy C ervical carcinomas arise as result of an uncontrolled persistent infection with a high-risk type of human papillomavirus (HPV), in particular, types 16 (HPV16) and 18 (HPV18), which account for approximately two-thirds of these cancers (1, 2). The HPV E6 and E7 proteins play a pivotal role in carcinogenesis and are expressed in both premalignant and advanced cervical lesions (3). Because HPV proteins are foreign to the body, one would expect the immune system to mount a response against these antigens when expressed in the cervical epithelium. Indeed, HPV16 E6-, E7-, and E2-specific Th1-and Th2-type CD4 ϩ T cell responses were frequently detected in peripheral blood mononuclear cell (PBMC) cultures of healthy individuals (4-6), showing that successful defense against HPV16 infection is commonly associated with the installment of a systemic effector T cell response against these viral antigens. In contrast, PBMC cultures from patients with HPV16-positive genital lesions either lacked detectable responses against HPV16 E6, E7, and E2 or displayed antigen-specific proliferative responses exhibiting a noninflammatory cytokine profile (5,7,8). Similarly, effective HPV18-specific T cell responses are only found in healthy controls but not in HPV18-positive patients (9). Taken together, these findings indicate that the development of high-risk HPVpositive cervical cancer is associated with failure of the HPVspecific T cell response.Studies in mouse models demonstrated that CD4 ϩ regulatory T cells play a critical role in curtailing effective immune responses against tumors (10, 11) and that these T cells can be primed in the same tumor-draining lymph nodes as their tumoricidal counterparts (12). Furthermore, analysis of tumor biopsies from melanoma patients revealed the presence of CD4 ϩ regulatory T cells recognizing the ...

Glioblastoma multiforme (GBM) is the most common primary brain tumor and is without exception lethal. GBMs modify the immune system, which contributes to the aggressive nature of the disease. Particularly, cells of the monocytic lineage, including monocytes, macrophages and microglia, are affected. We investigated the influence of GBM‐derived extracellular vesicles (EVs) on the phenotype of monocytic cells. Proteomic profiling showed GBM EVs to be enriched with proteins functioning in extracellular matrix interaction and leukocyte migration. GBM EVs appeared to skew the differentiation of peripheral blood‐derived monocytes to alternatively activated/M2‐type macrophages. This was observed for EVs from an established cell line, as well as for EVs from primary cultures of GBM stem‐like cells (GSCs). Unlike EVs of non‐GBM origin, GBM EVs induced modified expression of cell surface proteins, modified cytokine secretion (e.g., an increase in vascular endothelial growth factor and IL‐6) and increased phagocytic capacity of the macrophages. Most pronounced effects were observed upon incubation with EVs from mesenchymal GSCs. GSC EVs also affected primary human microglia, resulting in increased expression of Membrane type 1‐matrix metalloproteinase, a marker for GBM microglia and functioning as tumor‐supportive factor. In conclusion, GBM‐derived EVs can modify cells of the monocytic lineage, which acquire characteristics that resemble the tumor‐supportive phenotypes observed in patients.

No abstract

No abstract