Altered phenotype of blood dendritic cells in patients with acute pneumonia.

BACKGROUND: Dendritic cells (DCs) play a key role in the host defence against inhaled pathogens. However, the phenotype of blood DCs in patients with acute respiratory infections is unknown. OBJECTIVE: To investigate the number and the expression of function-associated molecules of blood DCs in patients with acute infectious pneumonia. METHODS: Sixteen patients with acute pneumonia and 19 controls without pneumonia were included in the study. The number as well as the expression of function-associated molecules of myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) were analysed in peripheral blood using four-colour flow cytometry. RESULTS: Elevated concentrations of procalcitonin (median: 0.55 ng/ml) and the rapid response to antibiotic treatment suggested a bacterial origin of the pneumonia in the patients. Total mDC (median: 27% of the controls) and pDC counts (median: 53% of the controls) were markedly reduced in patients with pneumonia, as compared to the controls. Percentages of blood mDCs, but not pDCs, were negatively correlated with serum concentrations of C-reactive protein. Patients with pneumonia were characterised by a significantly increased expression of Fc gamma receptors (CD32 and CD64) on mDCs and the Toll-like receptor 9 (TLR9) on pDCs. CONCLUSIONS: Circulating DCs are markedly reduced in patients with pneumonia, and characterised by an up-regulation of molecules recognising pathogen-associated molecular patterns and opsonised antigens.

Impact of immunotherapy on blood dendritic cells in patients with Hymenoptera venom allergy.

BACKGROUND: Modulation of T-cell differentiation, which is controlled by dendritic cells (DCs), plays a crucial role in specific immunotherapy (SIT). However, the number and the characteristics of blood DCs before and during immunotherapy are unknown. OBJECTIVE: To analyze the number and the characteristics of blood DC subsets in patients with Hymenoptera venom allergy before and after initiation of SIT. METHODS: In this clinical trial (NCT00947908), blood myeloid and plasmacytoid DCs were analyzed in 20 patients with Hymenoptera venom allergy (bee or wasp venom) by using 4-color flow cytometry at 3 time points: directly before SIT, and 52 hours and 12 months after initiation of SIT. In addition, 20 age-matched and sex-matched controls were examined. RESULTS: In patients with Hymenoptera venom allergy, the number of plasmacytoid DCs before SIT was comparable to that of controls. Plasmacytoid DCs decreased markedly 52 hours after initiation of SIT and returned to control levels after 12 months of treatment. Myeloid DCs were elevated in patients with Hymenoptera venom allergy before, during, and after the first 12 months of SIT. In addition, there were changes in the expression of function-associated surface molecules on myeloid DCs (such as Fc γ receptor 2 and Toll-like receptor 2) during SIT. CONCLUSION: Numbers of blood myeloid DCs are elevated in patients with Hymenoptera venom allergy, and there are specific changes in the expression of function-associated surface molecules on these cells during SIT. Numbers of plasmacytoid DCs in blood are profoundly but are only transiently decreased after initiation of SIT.

SAM levels, gene expression of SAM synthetase, methionine synthase and ACC oxidase, and ethylene emission from N. suaveolens flowers.

S'adenosyl-L: -methionine (SAM) is a ubiquitous methyl donor and a precursor in the biosynthesis of ethylene, polyamines, biotin, and nicotianamine in plants. Only limited information is available regarding its synthesis (SAM cycle) and its concentrations in plant tissues. The SAM concentrations in flowers of Nicotiana suaveolens were determined during day/night cycles and found to fluctuate rhythmically between 10 and 50 nmol g(-1) fresh weight. Troughs of SAM levels were measured in the evening and night, which corresponds to the time when the major floral scent compound, methyl benzoate, is synthesized by a SAM dependent methyltransferase (NsBSMT) and when this enzyme possesses its highest activity. The SAM synthetase (NsSAMS1) and methionine synthase (NsMS1) are enzymes, among others, which are involved in the synthesis and regeneration of SAM. Respective genes were isolated from a N. suaveolens petal cDNA library. Transcript accumulation patterns of both SAM regenerating enzymes matched perfectly those of the bifunctional NsBSMT; maximum mRNA accumulations of NsMS1 and NsSAMS1 were attained in the evening. Ethylene, which is synthesized from SAM, reached only low levels of 1-2 ppbv in N. suaveolens flowers. It is emitted in a burst at the end of the life span of the flowers, which correlates with the increased expression of the 1-aminocyclopropane-1-carboxylate oxidase (NsACO).