Estimated gray matter volume rapidly changes after a short motor task

Skill learning induces changes in estimates of gray matter volume (GMV) in the human brain, commonly detectable with magnetic resonance imaging (MRI). Rapid changes in GMV estimates while executing tasks may however confound between- and within-subject differences. Fluctuations in arterial blood flow are proposed to underlie this apparent task-related tissue plasticity. To test this hypothesis, we acquired multiple repetitions of structural T(1)-weighted and functional blood-oxygen level-dependent (BOLD) MRI measurements from 51 subjects performing a finger-tapping task (FTT; á 2 min) repeatedly for 30–60 min. Estimated GMV was decreased in motor regions during FTT compared with rest. Motor-related BOLD signal changes did not overlap nor correlate with GMV changes. Nearly simultaneous BOLD signals cannot fully explain task-induced changes in T(1)-weighted images. These sensitive and behavior-related GMV changes pose serious questions to reproducibility across studies, and morphological investigations during skill learning can also open new avenues on how to study rapid brain plasticity

Characterization of dendritic cell phenotype in allergic conjunctiva: increased expression of Fc epsilon RI, the high-affinity receptor for immunoglobulin E

Abstract PURPOSE: Dendritic cells (DCs) express the high-affinity receptor for IgE (Fc(epsilon)RI) on their surface, which may enhance their ability to capture and internalize antigens for presentation to T-lymphocytes. The aim of this study was to determine if expression of Fc(epsilon)RI(+) DCs is increased in the conjunctivae of vernal keratoconjunctivitis (VKC) patients compared with those of normal controls. METHODS: Conjunctival biopsies were obtained from non-atopic and VKC patients. Double immunohistochemical staining was carried out using antibodies against Fc(epsilon)RI and the CD1a antigen, a DC marker. The double-positive cells were counted in five representative fields of view for each conjunctival sample. RESULTS: Fc(epsilon)RI(+) CD1a(+) cells were present in significantly higher numbers in VKC conjunctivae compared with normal controls (mean cell count of 21.3 in VKC vs5.0 in controls, P<0.005). In normal patients the Fc(epsilon)RI-expressing DCs tended to be confined to the epithelial layer or the superficial substantia propria, but in the VKC samples these Fc(epsilon)RI(+) cells were mainly concentrated in the deeper substantia propria. CONCLUSIONS: Fc(epsilon)RI(+) DC numbers are elevated in the conjunctivae of VKC patients, a finding consistent with the results of other studies focusing on atopic conditions. Elevated expression of Fc(epsilon)RI on DCs would facilitate antigen presentation and enhance T-cell priming, thereby contributing to ocular symptoms

Characterisation of the phenotype and function of monocyte-derived dendritic cells in allergic conjunctiva

Abstract BACKGROUND: Dendritic cells (DCs) are the most potent antigen-presenting cells involved in initiating the immune response, presenting antigens to T cells and leading to T cell proliferation. In an immature state, DCs lack accessory signals required for T cell stimulation but are highly specialised to capture antigens. Full DC maturation changes the cell surface phenotype and facilitates stimulation of T cell proliferative responses. To examine the degree of DC maturity associated with vernal keratoconjunctivitis (VKC), the authors examined the phenotype and antigen-presentation capability of blood derived DCs from VKC patients and from normal controls. METHODS: Flow cytometry was used to identify the cell surface expression of markers of DC maturity (CD83, CD86, major histocompatibility complex class II) and mixed leucocyte reactions to assess DC induction of T cell proliferation. RESULTS: DCs derived from VKC patients were of a more mature phenotype than those from normal controls. However, these VKC DCs had reduced capability for induction of T cell proliferation compared with DCs from controls. CONCLUSION: The increased maturity of DCs in VKC patients correlates with the heightened immune responsiveness associated with this disorder. A number of mechanisms may underlie the impaired ability of DCs in atopy to stimulate T cell proliferation. This impairment of DC induction of T cell activation is likely to be one factor which contributes to the modified inflammatory response seen in VKC patients and the recognised susceptibility of these patients to viral infection

Characterisation of the phenotype and function of monocyte-derived dendritic cells in allergic conjunctiva

International audienceBackground: Dendritic cells (DCs) are the most potent antigen-presenting cells involved in initiating the immune response, presenting antigens to T cells and leading to T cell proliferation. In an immature state, DCs lack accessory signals required for T cell stimulation but are highly specialized to capture antigens. Full DC maturation changes the cell surface phenotype and facilitates stimulation of T cell proliferative responses. To examine the degree of DC maturity associated with vernal keratoconjunctivitis (VKC), we examined the phenotype and antigen-presentation capability of DCs derived from VKC patients and from normal controls. Methods: Flow cytometry was used to identify the cell surface expression of markers of DC maturity and mixed leukocyte reactions to assess DC induction of T cell proliferation. Results: DCs derived from VKC patients were of more mature phenotype than those from non-atopic controls. However, these VKC DCs had reduced capability for induction of T cell proliferation compared to DCs from controls. Conclusion: The increased maturity of DCs in VKC patients correlates with the heightened immune responsiveness associated with this disorder. A number of mechanisms may underlie the impaired ability of DCs in atopy to stimulate T cell proliferation. This impairment of DC induction of T cell activation is likely to be one factor which contributes to the modified inflammatory response seen in VKC patients and the recognised susceptibility of these patients to viral infection