Novel Targeting to XCR1+ Dendritic Cells Using Allogeneic T Cells for Polytopical Antibody Responses in the Lymph Nodes

Vaccination strategy that induce efficient antibody responses polytopically in most lymph nodes (LNs) against infections has not been established yet. Because donor-specific blood transfusion induces anti-donor class I MHC antibody production in splenectomized rats, we examined the mechanism and significance of this response. Among the donor blood components, T cells were the most efficient immunogens, inducing recipient T cell and B cell proliferative responses not only in the spleen, but also in the peripheral and gut LNs. Donor T cells soon migrated to the splenic T cell area and the LNs, with a temporary significant increase in recipient NK cells. XCR1+ resident dendritic cells (DCs), but not XCR1− DCs, selectively phagocytosed donor class I MHC+ fragments after 1 day. After 1.5 days, both DC subsets formed clusters with recipient CD4+ T cells, which proliferated within these clusters. Inhibition of donor T cell migration or depletion of NK cells by pretreatment with pertussis toxin or anti-asialoGM1 antibody, respectively, significantly suppressed DC phagocytosis and subsequent immune responses. Three allogeneic strains with different NK activities had the same response but with different intensity. Donor T cell proliferation was not required, indicating that the graft vs. host reaction is dispensable. Intravenous transfer of antigen-labeled and mitotic inhibitor-treated allogeneic, but not syngeneic, T cells induced a polytopical antibody response to labeled antigens in the LNs of splenectomized rats. These results demonstrate a novel mechanism of alloresponses polytopically in the secondary lymphoid organs (SLOs) induced by allogeneic T cells. Donor T cells behave as self-migratory antigen ferries to be delivered to resident XCR1+ DCs with negligible commitment of migratory DCs. Allogeneic T cells may be clinically applicable as vaccine vectors for polytopical prophylactic antibody production even in asplenic or hyposplenic individuals

FABP7 expression in normal and stab-injured brain cortex and its role in astrocyte proliferation

Reactive gliosis, in which astrocytes as well as other types of glial cells undergo massive proliferation, is a common hallmark of all brain pathologies. Brain-type fatty acid-binding protein (FABP7) is abundantly expressed in neural stem cells and astrocytes of developing brain, suggesting its role in differentiation and/or proliferation of glial cells through regulation of lipid metabolism and/or signaling. However, the role of FABP7 in proliferation of glial cells during reactive gliosis is unknown. In this study, we examined the expression of FABP7 in mouse cortical stab injury model and also the phenotype of FABP7-KO mice in glial cell proliferation. Western blotting showed that FABP7 expression was increased significantly in the injured cortex compared with the contralateral side. By immunohistochemistry, FABP7 was localized to GFAP+ astrocytes (21% of FABP7+ cells) and NG2+ oligodendrocyte progenitor cells (62%) in the normal cortex. In the injured cortex there was no change in the population of FABP7+/NG2+ cells, while there was a significant increase in FABP7+/GFAP+ cells. In the stab-injured cortex of FABP7-KO mice there was decrease in the total number of reactive astrocytes and in the number of BrdU+ astrocytes compared with wild-type mice. Primary cultured astrocytes from FABP7-KO mice also showed a significant decrease in proliferation and omega-3 fatty acid incorporation compared with wild-type astrocytes. Overall, these data suggest that FABP7 is involved in the proliferation of astrocytes by controlling cellular fatty acid homeostasis

Parvalbumin-positive Neurons in the Mouse A8 Region were Lesser than those in the Rat

Dopaminergic neurons play crucial roles in various physiological functions, such as reward, goal-directed behavior, memory formation, and pain sensation. One of the main dopaminergic cell groups in the brain is located in the retrorubral field (RRF, A8 region). A recent electrophysiological study using rats revealed that distinct neurons within the A8 region respond to the different degrees of the threat and aversive stimuli, and that the RRF is the origin of neural signals for threat and aversive outcomes. However, neurochemical characterization of the constituents of the A8 region is not enough. The aim of this study is to determine the neurochemical characteristics of these A8 neurons. To examine the neurochemical cellular organization of the A8 region, we performed immunohistochemistry for two GABAergic neuronal markers, parvalbumin (PV) and neuronal nitric oxide synthase (nNOS), in relation to tyrosine hydroxylase, a marker of dopaminergic neurons. We observed that the number of PV-positive neurons in the mouse A8 region was lesser than in rats. Moreover, nNOS-positive neurons were not detected within the A8 region in either species. These results indicate that the neurochemical organization of the A8 region was distinct between mice and rats. In addition, the cellular composition of the A8 dopaminergic cell group was distinct from other dopaminergic cell groups, such as the A9 and A10 region, in both mice and rats. Understanding these differences among species and cell groups is worth noting for translating the results obtained with distinct animal models into a clinical application

Quantitative relevance of substitutional impurities to carrier dynamics in diamond

International audienceWe have quantified substitutional impurity concentrations in synthetic diamond crystals down to sub-partsper-billion levels. The capture lifetimes of electrons and excitons injected via photoexcitation were compared for several samples with different impurity concentrations. Based on the assessed impurity concentrations, we have determined the capture cross section of electrons for boron impurity, σ A = 1 × 10 −14 cm 2 , and that of excitons for nitrogen impurity, σ ex D = 3 × 10 −14 cm 2. The general tendency of the mobility values for different carrier species is successfully reproduced by including carrier scattering by impurities and excitons