Search Results - (Author, Cooperation:M. A. Baird)

2015-09-01

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Actinin/analysis ; Actins/analysis ; Animals ; Cell Line ; Clathrin/analysis ; Clathrin-Coated Vesicles/chemistry/ultrastructure ; Coated Pits, Cell-Membrane/chemistry/ultrastructure ; Cytoskeleton/chemistry/metabolism/*ultrastructure ; *Endocytosis ; Endosomes/chemistry/ultrastructure ; Golgi Apparatus/ultrastructure ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional/instrumentation/*methods ; Microscopy, Fluorescence/instrumentation/*methods ; Mitochondria/chemistry/ultrastructure ; Organelles/chemistry/metabolism/*ultrastructure ; rab5 GTP-Binding Proteins/analysis

1365-3083

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Antigen presenting cells (APC) similar to immature dendritic cells can be generated in vitro from bone marrow precursors. The authors have compared the yield, the phenotype and the function of murine bone marrow cells cultured for 7 or 11 days in either granulocyte macrophage colony stimulating factor alone (GM BMAPC) or in combination with interleukin-4 (GM/IL-4 BMAPC). The results showed that GM/IL-4 BMAPC expressed the highest levels of MHC Class 2 molecules, CD86 /B7-2 and CD80/B7-1 co-stimulatory molecules and the lowest levels of F4/80 macrophage marker. However, when these APC were pulsed with BCG culture filtrate antigen or PPD they were not correspondingly more effective at stimulating activated T lymphocytes in vitro or priming naive T lymphocytes in vivo. Also, in contrast to GM BMAPC, high backgrounds recorded following injections of GM/IL-4 BMAPC without antigen were not consistently reduced by lowering the dose and irradiating the cells prior to administration. The authors conclude that the degree of maturity of BMAPC varies with culture conditions and that this may be an important consideration where BMAPC are to be used in vivo in immunotherapeutic regimens.

Electronic Resource

1365-3083

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Mycobacteria are capable of surviving and replicating in host macrophages, where they can release antigenic material into the environment. However, unlike dendritic cells (DCs), macrophages do not appear to be capable of activating naïve T cells. Therefore, this work investigated antigen transfer between macrophages and DCs. We generated culture supernatants from bacille Calmette–Guérin (BCG)-infected and uninfected macrophages and then determined whether DCs could present these extracellular mycobacterial antigens to T cells. Here, we show that DCs pulsed with antigens released from BCG-infected macrophages can stimulate primed T cells in vitro and initiate naïve T-cell responses in vivo. These results suggest that antigen transfer can occur between macrophages and DCs.

Electronic Resource

1365-3083

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The ability of B cells to act as effective antigen-presenting cells is a source of debate which centres on the degree of activation of either B cells or T cells. We have investigated whether B cells treated with interleukin 4 (IL-4) can express the two signals required to activate T cells: MHC Class 2/antigenic peptide complexes(signal 1) and the costimulatory molecules B7-1 and B7-2 (signal 2). We have also determined whether these cells could activate atitigen-experienced T cells in vitro and whether they could prime naive T cells in vivo. We found that B cells expressed abutidant MHC Class 2 molecules and moderate levels of B7-2 after 24 h culture in IL-4 with or without purified protein derivative (PPD) but B7-1 was not detectable. PPD-pulsed, IL-4 treated B cells induced antigeti-experienced T cells to proliferate in vitro but these cells failed to prime naive T cells in vivo when injected itito mice. We conclude that signals, in addition to those mduced with IL-4, are required for B cells to initiate an immutie respotise to atitigen.

Electronic Resource

1573-5036

low temperature ; N assimilation ; N2 fixation ; NH 4 + ; NO 3 − ; white clover

Springer Online Journal Archives 1860-2000

Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Abstract White clover plants were grown for 97 days under two temperature regimes (20/15°C and 8/5°C day/night temperatures) and were supplied with either small amounts (a total of 80 mg N pot−1) of ammonium (NH 4 + ) or nitrate (NO 3 − ) nitrogen, or received no mineral N and relied on N2 fixation. Greatest growth and total leaf area of clover plants occurred in N2 fixing and NO 3 − -fed plants grown at 20/15°C and poorest growth occurred in NH 4 + -fed plants grown at 8/5°C. Nodule mass per plant was greater at 8/5°C due to increased nodule numbers rather than increased dry weight per nodule. This compensated to some extent for the reduced N2-fixing activity per unit dry weight of nodule tissue found at the low growth temperature up to 116 d after sowing, but thereafter both activity per nodule dry weight and activity per plant were greater at the low temperature. Highest nitrate reductase activity (NRA) per g fresh weight and total activity per leaf, petiole or root occurred in NO 3 − -fed plants at 8/5°C. Low growth temperature resulted in a greater partitioning of total plant NRA to the roots of NO 3 − -fed plants. The results are considered in relation to the use of N fertiliser in the spring under field conditions.

Electronic Resource