Objective-To determine if the levels of circulating myeloid-derived suppressor cells increase with progression of prostate cancer (PCa); to determine if such cells could contribute to the relative inefficiency of PCa immunotherapy.Materials and Methods-We analyzed peripheral blood mononuclear cells isolated from untreated PCa patients (uPCa; N = 18; mean age ± SD: 72.1 ± 6.9 years), tPCa (N = 22; 72.8 ± 9.8 years) and age matched controls (AMC; N = 12; 68.8 ± 7.5 years). We quantified surface marker phenotype, differentiation potential, effects on T cell proliferation and intracellular cytokines.Results-We observed an unexpectedly high percentage of a type of myeloid-derived suppressor cells, CD14 + HLA-DR low/− monocytes, in tPCa (30.7 ± 15.0% of CD14 + cells) relative to AMC (4.1 ± 6.5%, P < 0.0001) and uPCa (10.6 ± 14.3%, P = 0.0001). The levels of CD14 + HLA-DR low/− cells were significantly correlated with circulating PSA levels and treatment with LHRH-agonist leuprolide in combination with either an antiandrogen or dexamethasone. Monocytes from tPCa inhibited autologous T cell proliferation statistically significantly more effectively than AMC monocytes and were defective in their ability to differentiate into phenotypically mature dendritic cells. Isolated CD14 + HLA-DR low/− cells expressed higher levels of intracellular interleukin-10 and suppressed T cell proliferation more effectively than isolated CD14 + HLA-DR + cells.Conclusions-This is the first report of CD14 + cells exhibiting reduced expression of HLA-DR molecules in PCa patients. These cells suppress immune cell function in vitro and, plausibly, in vivo, a finding that must be factored into the design of immunotherapy protocols for PCa patients.
IntroductionImatinib mesylate (Gleevec; Novartis, Basel, Switzerland) is a reversible tyrosine kinase inhibitor effective in treatment of chronic myelogenous leukemia 1 (CML), gastrointestinal stromal tumors, 2,3 eosinophilic disorders, 4 and systemic mast cell disease 5 and has been tried in several other diseases. 6,7 The drug binds preferentially to adenosine triphosphate (ATP)-binding sites of the c-kit protooncogene product, platelet-derived growth factor receptor (PDGF-R), and Abelson kinase (c-ABL) [8][9][10] impeding the ensuing signal transduction (for a review, see Savage and Antman 11 ). Inhibition of the ABL portion of the BCR-ABL fusion protein, pathognomonic of CML, 12 is the basis of imatinib mesylate efficacy in inducing hematologic and cytogenetic remissions in CML. 1,13 Inhibition of c-KIT is considered critical for imatinib mesylate effects in gastrointestinal stromal tumors 14 and mast cell disease. 5 In our efforts to develop immunotherapy for CML, 15,16 we studied the effects of imatinib mesylate on the development of CML-specific immunity on administration of autologous mature dendritic cells (DCs). Consequently, we measured the effects of imatinib mesylate on in vitro correlates of immunity. 17 At concentrations of 5 M, achieved in the serum of patients on the standard therapeutic dose of 400 mg/d, 1 the drug was cytostatic, it arrested transit into the S phase of the cell cycle, and it impeded in vitro proliferation of human normal and leukemic T cells. We analyzed the effects of imatinib mesylate on the activity of intracellular signal transduction molecules associated with the control of T-cell function. The drug diminished phosphorylation of Lck, ERK 1/2, and Rb proteins and reduced the levels of cyclin D3 and of activated nuclear transcription factor B (NF-B). In addition, imatinib mesylate inhibited delayed-type hypersensitivity (DTH) in mice without affecting T-cell numbers, indicating that the drug inhibits T-cell response but does not induce apoptosis. Materials and methods Cells and reagentsT cells were isolated by negative immunoadsorption (Pan T kit; Miltenyi Biotec, Auburn, CA), pooled from 3 or more normal donors and cryopreserved until use. On thawing, the cells were incubated in X-VIVO 15 medium (BioWhittaker, Walkersville, MD) supplemented with 1.0% human AB serum (Sigma, St Louis, MO), in a humidified atmosphere of 5.0% CO 2 at 37°C. For experiments longer than 1 day, the medium contained 1.0% penicillin/streptomycin solution (Sigma) as well. Human acute T-cell leukemia cells Jurkat (ATCC TIB-152), acute T lymphoblastic leukemia cells CCRF-CEM (ATCC CCL-119), and hematopoietic malignant K-562 cells (ATCC CCL-243), were obtained from American Type Culture Collection (Manassas, VA) and cultured under the same conditions. Allogeneic DCs were derived from CD14 ϩ cells and cultured with T cells as previously described. 16 Imatinib mesylate (Novartis) was dissolved in dimethyl sulfoxide (DMSO) to a final concentration of 10 mM. The stock solution was stored at Ϫ20°C until use,...
We wished to determine the applicability of previously proposed deterministic mathematical models to description of growth of multicellular tumour spheroids. The models were placed into three general classes: empirical, functional and structural. From these classes, 17 models were applied systematically to growth curves of multicellular tumour spheroids used as paradigms of prevascular and microregional tumour growth. The spheroid growth curves were determined with uniquely high density of measurements and high precision. The theoretical growth curves obtained from the models were fitted by the weighted least-squares method to the 15 measured growth curves, each corresponding to a different cell line. The classical growth models such as von Bertalanffy, logistic and Gompertz were considered as nested within more general models. Our results demonstrate that most models fitted the data fairly well and that criteria other than statistical had to be used for final selection. The Gompertz, the autostimulation and the simple spheroid models were the most appropriate for spheroid growth in the empirical, functional and structural classes of models, respectively. We also showed that some models (e.g. logistic, von Bertalanffy) were clearly inadequate. Thus, contrary to the widely held belief, the sigmoid character of a three or more parameter growth function is not sufficient for adequate fits.
LRSCs are a novel source of fully functional PBMNCs that can replace the more traditional sources of research-grade cellular products.
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