24 research outputs found
Human Macrophages and Dendritic Cells Can Equally Present MART-1 Antigen to CD8+ T Cells after Phagocytosis of Gamma-Irradiated Melanoma Cells
Dendritic cells (DC) can achieve cross-presentation of naturally-occurring
tumor-associated antigens after phagocytosis and processing of dying tumor
cells. They have been used in different clinical settings to vaccinate cancer
patients. We have previously used gamma-irradiated MART-1 expressing melanoma
cells as a source of antigens to vaccinate melanoma patients by injecting
irradiated cells with BCG and GM-CSF or to load immature DC and use them as
a vaccine. Other clinical trials have used IFN-gamma activated macrophage
killer cells (MAK) to treat cancer patients. However, the clinical use of
MAK has been based on their direct tumoricidal activity rather than on their
ability to act as antigen-presenting cells to stimulate an adaptive antitumor
response. Thus, in the present work, we compared the fate of MART-1 after
phagocytosis of gamma-irradiated cells by clinical grade DC or MAK as well
as the ability of these cells to cross present MART-1 to CD8+
T cells. Using a high affinity antibody against MART-1, 2A9, which specifically
stains melanoma tumors, melanoma cell lines and normal melanocytes, the expression
level of MART-1 in melanoma cell lines could be related to their ability to
stimulate IFN-gamma production by a MART-1 specific HLA-A*0201-restricted
CD8+ T cell clone. Confocal microscopy with Alexa Fluor®647-labelled
2A9 also showed that MART-1 could be detected in tumor cells attached and/or
fused to phagocytes and even inside these cells as early as 1 h and up to
24 h or 48 h after initiation of co-cultures between gamma-irradiated melanoma
cells and MAK or DC, respectively. Interestingly, MART-1 was cross-presented
to MART-1 specific T cells by both MAK and DC co-cultured with melanoma gamma-irradiated
cells for different time-points. Thus, naturally occurring MART-1 melanoma
antigen can be taken-up from dying melanoma cells into DC or MAK and both
cell types can induce specific CD8+ T cell cross-presentation
thereafter
Therapeutic T cells induce tumor-directed chemotaxis of innate immune cells through tumor-specific secretion of chemokines and stimulation of B16BL6 melanoma to secrete chemokines
Background: The mechanisms by which tumor-specific T cells induce regression of established metastases are not fully characterized. In using the poorly immunogenic B16BL6-D5 (D5) melanoma model we reported that T cell-mediated tumor regression can occur independently of perforin, IFN-gamma or the combination of both. Characterization of regressing pulmonary metastases identified macrophages as a major component of the cells infiltrating the tumor after adoptive transfer of effector T cells. This led us to hypothesize that macrophages played a central role in tumor regression following T-cell transfer. Here, we sought to determine the factors responsible for the infiltration of macrophages at the tumor site. Methods: These studies used the poorly immunogenic D5 melanoma model. Tumor-specific effector T cells, generated from tumor vaccine-draining lymph nodes (TVDLN), were used for adoptive immunotherapy and in vitro analysis of chemokine expression. Cellular infiltrates into pulmonary metastases were determined by immunohistochemistry. Chemokine expression by the D5 melanoma following co-culture with T cells, IFN-gamma or TNF-alpha was determined by RT-PCR and ELISA. Functional activity of chemokines was confirmed using a macrophage migration assay. T cell activation of macrophages to release nitric oxide (NO) was determined using GRIES reagent. Results: We observed that tumor-specific T cells with a type 1 cytokine profile also expressed message for and secreted RANTES, MIP-1 alpha and MIP-1 beta following stimulation with specific tumor. Unexpectedly, D5 melanoma cells cultured with IFN-gamma or TNF-alpha, two type 1 cytokines expressed by therapeutic T cells, secreted Keratinocyte Chemoattractant (KC), MCP-1, IP-10 and RANTES and expressed mRNA for MIG. The chemokines released by T cells and cytokine-stimulated tumor cells were functional and induced migration of the DJ2PM macrophage cell line. Additionally, tumor-specific stimulation of wt or perforin-deficient (PKO) effector T cells induced macrophages to secrete nitric oxide (NO), providing an additional effector mechanism for T cell-mediated tumor regression. Conclusion: These data suggest two possible sources for chemokine secretion that stimulates macrophage recruitment to the site of tumor metastases. Both appear to be initiated by T cell recognition of specific antigen, but one is dependent on the tumor cells to produce the chemokines that recruit macrophages
The PtdIns 3-Kinase/Akt Pathway Regulates Macrophage-Mediated ADCC against B Cell Lymphoma
Macrophages are important effectors in the clearance of antibody-coated tumor cells. However, the signaling pathways that regulate macrophage-induced ADCC are poorly defined. To understand the regulation of macrophage-mediated ADCC, we used human B cell lymphoma coated with Rituximab as the tumor target and murine macrophages primed with IFNγ as the effectors. Our data demonstrate that the PtdIns 3-kinase/Akt pathway is activated during macrophage-induced ADCC and that the inhibition of PtdIns 3-kinase results in the inhibition of macrophage-mediated cytotoxicity. Interestingly, downstream of PtdIns 3-kinase, expression of constitutively active Akt (Myr-Akt) in macrophages significantly enhanced their ability to mediate ADCC. Further analysis revealed that in this model, macrophage-mediated ADCC is dependent upon the release of nitric oxide (NO). However, the PtdIns 3-kinase/Akt pathway does not appear to regulate NO production. An examination of the role of the PtdIns 3-kinase/Akt pathway in regulating conjugate formation indicated that macrophages treated with an inhibitor of PtdIns 3-kinase fail to polarize the cytoskeleton at the synapse and show a significant reduction in the number of conjugates formed with tumor targets. Further, inhibition of PtdIns 3-kinase also reduced macrophage spreading on Rituximab-coated surfaces. On the other hand, Myr-Akt expressing macrophages displayed a significantly greater ability to form conjugates with tumor cells. Taken together, these findings illustrate that the PtdIns 3-kinase/Akt pathway plays a critical role in macrophage ADCC through its influence on conjugate formation between macrophages and antibody-coated tumor cells
CpG-oligodeoxynucleotides exert remarkable antitumor activity against diffuse malignant peritoneal mesothelioma orthotopic xenografts
Production and characterization of recombinant mature Amb a 11, a new major allergen of short ragweed (Ambrosia artemisiifolia) pollen with a cysteine protease activity
Production and characterization of recombinant mature Amb a 11, a new major allergen of short ragweed (Ambrosia artemisiifolia) pollen with a cysteine protease activity. 34th. European Academy of Allergy and Clinical Immunology (EAACI
Distinct roles for IFN regulatory factor (IRF)-3 and IRF-7 in the activation of antitumor properties of human macrophages
NRC publication: Ye
Distinct roles for IFN regulatory factor (IRF)-3 and IRF-7 in the activation of antitumor properties of human macrophages
NRC publication: Ye
Comparison between major histocompatibility complex class II tetramer staining and surface expression of activation markers for the detection of allergen-specific <tex>CD4^{+}$</tex> T cells
Structural and functional characterization of the cysteine protease Amb a 11, a new major allergen from short ragweed (Ambrosia artemisiifolia) pollen
Structural and functional characterization of the cysteine protease Amb a 11, a new major allergen from short ragweed ([i]Ambrosia artemisiifolia[/i]) pollen. Meeting of the European-Academy-of-Allergy-and-Clinical-Immunolog