Klebsiella pneumoniae-triggered DC recruit human NK cells in a CCR5-dependent manner leading to increased CCL19-responsiveness and activation of NK cells.

Besides their role in destruction of altered self-cells, NK cells have been shown to potentiate T-cell responses by interacting with DC. To take advantage of NK-DC crosstalk in therapeutic DC-based vaccination for infectious diseases and cancer, it is essential to understand the biology of this crosstalk. We aimed to elucidate the in vitro mechanisms responsible for NK-cell recruitment and activation by DC during infection. To mimic bacterial infection, DC were exposed to a membrane fraction of Klebsiella pneumoniae, which triggers TLR2/4. DC matured with these bacterial fragments can actively recruit NK cells in a CCR5-dependent manner. An additional mechanism of DC-induced NK-cell recruitment is characterized by the induction of CCR7 expression on CD56(dim) CD16(+) NK cells after physical contact with membrane fraction of K. pneumoniae-matured DC, resulting in an enhanced migratory responsiveness to the lymph node-associated chemokine CCL19. Bacterial fragment-matured DC do not only mediate NK-cell migration but also meet the prerequisites needed for augmentation of NK-cell cytotoxicity and IFN-γ production, the latter of which contributes to Th1 polarization.

Elimination of the chemotherapy resistant subpopulation of 4T1 mouse breast cancer by haploidentical NK cells cures the vast majority of mice.

Metastatic breast cancer is currently incurable despite initial responsiveness, assumingly due to the presence of chemoresistant subpopulations that can be characterized as label retaining cells (LRC). In the 4T1 mouse breast cancer model, we previously achieved cure after Cyclophosphamide and Total Body Irradiation (CY + TBI) followed by haploidentical bone marrow and spleen transplantation (BMSPLT). CY + TBI without transplantation induced only transient impaired tumor growth indicating a critical role of donor immune cells. As it remained unknown if the 4T1 model resembles human disease with respect to the presence of subpopulations of chemoresistant LRC, we now demonstrate this is indeed the case. Chemoresistance of 4T1 LRC was demonstrated by in vitro co-incubation of fluorescently labeled 4T1 cells in limiting dilution with cyclophosphamide, doxorubicin or cisplatinum, after which only LRC containing colonies remained. LRC also remain in vivo after treatment with CY + TBI. Succeeding experiments set up to identify the haploidentical effector cell responsible for cure and, therefore, for the elimination of chemoresistant LRC designate donor NK cells crucial for the anti-tumor effect. NK cell depletion of the haploidentical graft fully abrogated the anti-tumor effect. Increased disease-free survival retained after transplantation of haploidentical bone marrow and NK cell-enriched spleen cell grafts, even in the absence of donor T-cells or of donor bone marrow. Tumor growth analysis indicates the anti-tumor effect being immediate (days). Based on these data, it is worthwhile to explore alloreactive adoptive NK cell therapy as consolidation for patients with metastasized breast cancer.

Expression of aberrantly glycosylated Mucin-1 in ovarian cancer.

AIMS: Mucin 1 (MUC1) is an important tumour-associated antigen (TAA), both overexpressed and aberrantly glycosylated in adenocarcinomas. The aim of this study was to examine the MUC1-glycosylation status of primary ovarian adenocarcinomas and metastatic lesions. METHODS AND RESULTS: Paraffin-embedded tissue sections of 37 primary ovarian adenocarcinomas representing all histotypes (22 serous, five mucinous, two clear-cell, eight endometrioid), four serous borderline tumours with intraepithelial carcinoma, seven sections of ovarian endometriosis and 13 metastatic lesions were analysed by immunohistochemistry. Non-neoplastic ovarian surface epithelium and serous cystadenomas were used as controls. All epithelia expressed MUC1 protein. Of primary tumours, 76% expressed the differentiation-dependent glycoform and 84% the cancer-associated glycoform (Tn/Sialyl-Tn-epitopes). In metastatic lesions this was 77% and 85%, respectively. Notably, in 57% of ovarian endometriosis and 75% of intraepithelial lesions, the cancer-associated MUC1 epitopes were expressed, whereas normal ovarian surface epithelium and serous cystadenomas did not express these epitopes. CONCLUSIONS: The underglycosylated MUC1 epitopes are expressed by all histotypes of primary ovarian adenocarcinomas, by the vast majority of metastatic lesions and by possible ovarian cancer precursor lesions, but not by normal ovarian tissue. These results indicate that MUC1-associated Tn/STn-epitopes are important targets for immunotherapy and diagnostic imaging in ovarian cancer patients.