Effect of prostaglandin E2, lipopolysaccharide, IFN-gamma and cytokines on the generation and function of fast-DC

BACKGROUND

Recent reports have described a new strategy for differentiation and maturation of monocyte-derived DC within only 48 h of in vitro culture (fast-DC). We compared the ability of various maturation stimuli with the generation of Ag-specific T-cell responses and generation of functional fast-DC.

METHODS

CD14+ cells were treated with GM-CSF and IL-4 for 1 day to generate immature DC, and were then matured with either inflammatory cytokines or a combination of lipopolysaccharide (LPS) and INF-gamma. Mature DC were then used to study the effect of prostaglandin E2 (PGE2) on the stimulatory function of fast-DC.

RESULTS

fast-DC were CD14- and expressed mature DC surface markers, and maintained this phenotype after withdrawing the cytokine from culture. Treatment of fast-DC with a combination of LPS and INF-gamma promoted the maturation of highly uniform fast-DC. The T-cell proliferative response to DC was enhanced by inclusion of PGE2 in the MCM-mimic (TNF-a, IL-1 a, IL-6, PGE2) cocktail.

DISCUSSION

fast-DC are very effective; they not only reduce the labor, cost and time required for in vitro DC development, but may also represent a model more closely resembling DC differentiation from monocytes in vivo.

Generation of Ag-specific cytotoxic T lymphocytes by DC transfected with in vitro transcribed influenza virus matrix protein (M1) mRNA

BACKGROUND

Application of DC transfected with tumor Ag RNA is promising for DC-based tumor immunotherapy. In this study, Ag-specific cytotoxic T lymphocytes (CTL) were generated by priming lymphocytes with DC transfected with in vitro transcribed (IVT) influenza virus matrix protein M1 (M1) mRNA.

METHODS

Human UC blood-CD34+ cell-derived DC were transfected with IVT mRNA encoding either the enhanced green fluorescence protein (EGFP), or M1 by square-wave electroporation. DC were confirmed to have typical morphology and phenotype. DC transfected with IVT EGFP mRNA were analyzed with the FACScan flow cytometer, to confirm the efficiency of this transfection method. On Days 7, 14, 21 and 28 after the start of DC culture, DC were harvested and electroporated with M1 mRNA. The transfected DC were co-cultured with autologous UC blood CD34- cells. One week after the fourth priming of autologous CD34 negative cells with M1 mRNA electroporated DC, Ag-specific CTL activity was evaluated. To prepare target cells, M1 mRNA was added to autologous DC 48 h prior to CTL assays.

RESULTS

Our CTL assays results indicate that UC blood CD34+ cell-derived DC transfected with M1 mRNA by electroporation stimulated Ag-specific CTL responses that are capable of recognizing and lysing autologous DC loaded with M1 mRNA. M1 mRNA transfected DC-primed CTL showed a significant cytotoxic activity against M1 mRNA loaded autologous DC, while nearly baseline cytotoxic activity was recorded for the M1 mRNA unloaded DC.

DISCUSSION

Our results showed that mRNA-transfected DC are potent stimulators of T-cell immunity in vitro. In addition, mRNA-loaded DC can function as targets in CTL cytotoxicity assays, which offer a practical substitute for tumor cells in assays to test the immunological effects of specific Ags.

Generation of dendritic cells from leukaemia cells of a patient with acute promyelocytic leukaemia by culture with GM-CSF, IL-4 and TNF-alpha

Dendritic cells are potent antigen-presenting cells derived from CD34+ haemopoietic stem cells. Dendritic cells have been reported to be generated from cells in granulocytic lineage as well as monocytes, blood dendritic cell precursors and lymphoid progenitors. In order to explore the differentiation pathway of dendritic cells from granulocytic cells and the applicability of leukaemia-derived dendritic cells for anti-leukaemic immunotherapy in acute leukaemia of granulocytic origin, we tried to generate dendritic cells from leukaemia cells of a patient with acute promyelocytic leukaemia (APL). Leukaemia cells were cultured with GM-CSF, IL-4 and TNF-alpha for 10 days. Azurophilic granule-containing cells with marked cytoplasmic projections were generated in the culture. FACS analysis of these cultured cells revealed the generation of CD1a+, CD83+, CD80+, CD86+, CD40+ and HLA-DR+ cells. The leukaemic origin of these dendritic-like cells was demonstrated by in situ hybridization of magnetic-bead-sorted CD1a+ dendritic cells using the DNA probes of t(15;17). Cells generated by culturing leukaemia cells were demonstrated to have a potent antigen-presenting function in allogeneic mixed leucocyte cultures. These findings show the plausibility of the previously reported pathway of dendritic cell maturation through granulocytic cells and suggest the possibility of anti-leukaemic immunotherapy using leukaemia-derived dendritic cells even in patients with acute promyelocytic leukaemia.

Dipole defects in Al2O3:Mg,Cr

In this work, dipole defects are investigated applying the thermally stimulated depolarisation currents (TSDC) technique. The TSDC spectra of Al2O3 doped with Mg and Cr show two bands centred at 230 K and 250 K, respectively. The maximum intensity of the bands increases linearly with the polarisation field, a typical behaviour of defects with dipole origin. An increase of the band at 250 K with gamma irradiation has been observed and a thermal decrease of the bands for heat treatments between 1000 K and 1400 K. Above this temperature the bands are partially recovered. Impurity neutron activation analysis shows that magnesium. chromium and iron content varies from 15 to 60 ppm. Optical absorption (AO) measurements show a broad band centred in 2.6 eV (21000 cm(-1)) associated with trapped holes localised on an O- ion adjacent to a cation site which is deficient in positive charge. It has been assumed that a substitutional Mg2+ ion occupies the cation site near a trapped hole on one of the six oxygen ions surrounding the magnesium impurity giving rise to the dipole responsible for the observed TSDC bands. Calculations carried out through defect simulation methods confirm that the probability of Al3+ being replaced by Mg2+ is higher than Mn2+, Co2+, Fe2+ and Cr2+.