Phenotypically distinct subsets of CD4+ T cells induce or protect from chronic intestinal inflammation in C. B-17 scid mice

CD4⁺ T cells in the mouse can be subdivided into two fractionsbased on the level of expression of the CD45RB determinant.Previous studies have shown that these subsets are functionallydistinct. We have further characterized the properties of thesesubpopulations in vivo by injecting them into C. B-17 scid mice.The animals restored with the CD45RB^highCD4⁺ T cell populationdeveloped a lethal wasting disease with severe mononuclear cellinfiltrates into the colon and elevated levels of IFN- mRNA.In contrast, animals restored with the reciprocal CD45RB^lowsubset or with unfractionated CD4⁺ T cells did not develop thewasting or colitis. Importantly, the co-transfer of the CD45RB^lowpopulation with the CD45RB^high population prevented the wastingdisease and colitis. These data indicate that important regulatoryinteractions occur between the CD45RB^high and CD45RB^lowCD4⁺T cell subsets and that disruption of this mechanism has fatalconsequences.     

Defective suppression of Th2 cytokines by CD4+CD25+ regulatory T cells in birch allergics during birch pollen season

BACKGROUND: CD4(+)CD25+ regulatory T cells suppress proliferation and cytokine production by human T cells both to self-antigens and exogenous antigens. Absence of these cells in human newborns leads to multiple autoimmune and inflammatory disorders together with elevated IgE levels. However, their role in human allergic disease is still unclear. OBJECTIVE: This study aimed to evaluate the capacity of CD4(+)CD25+ regulatory T cells to suppress proliferation and cytokine production outside and during birch-pollen season in birch-allergic patients relative to non-allergic controls. METHODS: CD4+ cells were obtained from blood of 13 birch-allergic patients and six non-allergic controls outside pollen season and from 10 birch-allergic patients and 10 non-allergic controls during birch-pollen season. CD25+ and CD25- fractions were purified with magnetic beads and cell fractions, alone or together in various ratios, were cultured with antigen-presenting cells and birch-pollen extract or anti-CD3 antibody. Proliferation and levels of IFN-gamma, IL-13, IL-5 and IL-10 were measured by thymidin incorporation and ELISA, respectively. Numbers of CD25+ cells were analysed by flow cytometry. RESULTS: CD4(+)CD25+ regulatory T cells from both allergics and non-allergics potently suppressed T cell proliferation to birch allergen both outside and during birch-pollen season. However, during season CD4(+)CD25+ regulatory T cells from allergic patients but not from non-allergic controls were defective in down-regulating birch pollen induced IL-13 and IL-5 production, while their capacity to suppress IFN-gamma production was retained. In contrast, outside pollen season the regulatory cells of both allergics and non-allergic controls were able to inhibit T-helper 2 cytokine production. CONCLUSION: This is the first study to show differential suppression of Th1 and Th2 cytokines, with CD4(+)CD25+ regulatory T cells from birch-pollen-allergic patients being unable to down-regulate Th2, but not Th1 responses during birch-pollen season.     

中国恒河猴(Macaca mulatta)外周血CD4+CD25+T淋巴细胞的研究

目的:研究中国恒河猴外周血中CD4 CD25 T淋巴细胞亚群及其分布频率。方法:利用流式细胞术对50只中国恒河猴外周血CD4 CD25 T淋巴细胞进行了分析。结果:发现所有被检测的恒河猴个体中均存在明显的CD4 CD25 T淋巴细胞亚群;CD4 CD25 T淋巴细胞大约占CD4 T淋巴细胞的9.1%(变化范围为2.6%～18.1%);其中CD4 CD25highT淋巴细胞约占2.5%(0.3%～5.5%)。对不同年龄和性别个体中CD4 CD25 T淋巴细胞频率的初步分析未发现统计学上有年龄或性别差异。结论:中国恒河猴可用于与CD4 CD25 T细胞相关的人类疾病的研究中。     

CD4+CD25+调节性T细胞与系统性红斑狼疮病情活动性关系的研究

目的：检测系统性红斑狼疮患者外周血CD4^＋CD25^＋、CD4^＋CD8^＋调节性T细胞亚群，探讨其与疾病活动性、肾脏损伤、血清抗ds-DNA抗体及免疫球蛋白和补体C3含量的关系。方法：采用流式细胞术检测北京协和医院住院和门诊SLE患者（n=37）外周血CD4^＋CD25^＋T、CD4^＋CD8^＋T细胞群比例，以15例RA和15例SS组成自身免疫性疾病对照，30例健康体检者作为正常对照，观察调节性T细胞亚群与SLE患者疾病活动性指标SLEDAI、IgG、C3及血清抗ds-DNA抗体的关系。结果：①疾病活动期SLE患者外周血CD4^＋CD25^＋调节性T细胞群比例显著低于正常对照组（P〈0.01），疾病稳定期和风湿性疾病对照组与正常对照组结果差异无统计学意义。疾病活动期和稳定期SLE患者CD4＋CD8＋T细胞群比例都略高于正常对照组，但未发现结果差异有统计学意义（P〉0.05）。②疾病活动期SLE患者外周血CD4^＋CD25^＋T细胞比例及CD4^＋CD25^＋/CD4^＋值显著低于稳定期患者（P〈0.01）。SLE患者外周血CD4^＋CD25^＋/CD4^＋值与SLEDAI、补体C3呈低度相关（r分别为-0.491、0.368，P〈0.05），CD4^＋CD25^＋T细胞数量与SLEDAI呈负相关（r=-0.578，P〈0.05）。③SLE并发肾病组外周血CD4^＋CD25^＋T细胞群比例及CD4^＋CD25^＋/CD4^＋值显著低于非肾病组（P〈0.01；P〈0.05）。同一SLE患者治疗前后CD3^＋CD4^-CD8^-细胞和NK细胞降低，CD4^＋CD25^＋细胞、CD4^＋CD25^＋/CD4^＋值及CD8^＋T细胞增加，但未发现这些结果差异有统计学意义。本次研究未发现NK细胞、CD4^＋CD8＋T细胞、CD4^＋CD25^＋T细胞群比例在ds-DNA＋组与ds-DNA-组之间结果差异有统计学意义。结论：SLE患者外周血CD4^＋CD25^＋T细胞群比例与SLEDAI成负相关，与肾脏的损害也有密切关系，但与血清抗ds-DNA抗体产生的关系不明显。活动期SLE患者外周血CD4^＋CD25^＋T细胞减少，稳定期CD4^＋CD25^＋T细胞比例回升，因此推测CD4^＋CD25^＋T细胞的变化可能是导致疾病发生和病情发展及相关器官（如肾脏）损伤的关键环节之一。     

“Dark” (compacted) neurons may not die through the necrotic pathway

Dark neurons were produced in the cortex of the rat brain by hypoglycemic convulsions. In the somatodendritic domain of each affected neuron, the ultrastructural elements, except for disturbed mitochondria, were remarkably preserved during the acute stage, but the distances between them were reduced dramatically (ultrastructural compaction). Following a 1-min convulsion period, only a few neurons were involved and their environment appeared undamaged. In contrast, 1-h convulsions affected many neurons and caused swelling of astrocytic processes and neuronal dendrites (excitotoxic neuropil). A proportion of dark neurons recovered the normal structure in 2 days. The non-recovering dark neurons were removed from the brain cortex through two entirely different pathways. In the case of 1-h convulsions, their organelles swelled, then disintegrated and finally dispersed into the neuropil through large gaps in the plasma membrane (necrotic-like removal). Following a 1-min convulsion period, the non-recovering dark neurons fell apart into membrane-bound fragments that retained the compacted interior even after being engulfed by astrocytes or microglial cells (apoptotic-like removal). Consequently, in contrast to what is generally accepted, the dark neurons produced by 1-min hypoglycemic convulsions do not die as a consequence of necrosis. As regards the case of 1-h convulsions, it is assumed that a necrotic-like removal process is imposed, by an excitotoxic environment, on dark neurons that previously died through a non-necrotic pathway. Apoptotic neurons were produced in the hippocampal dentate gyrus by intraventricularly administered colchicine. After the biochemical processes had been completed and the chromatin condensation in the nucleus had reached an advanced phase, the ultrastructural elements in the somatodendritic cytoplasm of the affected cells became compacted. If present in an apparently undamaged environment such apoptotic neurons were removed from the dentate gyrus through the apoptotic sequence of morphological changes, whereas those present in an impaired environment were removed through a necrotic-like sequence of morphological changes. This suggests that the removal pathway may depend on the environment and not on the death pathway, as also assumed in the case of the dark neurons produced by hypoglycemic convulsions.     

The majority of human CD3 epitopes are conferred by the epsilon chain

Transgenic mouse T cells expressing the human CD3 chain bindthe majority (29/36) of monoclonal antibodies (mAbs) specificfor human CD3. A proportion of these mAbs are also able to recognizeisolated CD3 in a soluble, recombinant form. Thus, CD3 can confermost CD3 epitopes on the TCR-CD3 complex, but many determinantsmay require assembly of the complex for their formation. A numberot mAbs did not recognize -transgenic T cells and probably needother CD3 subunits for binding. CD3-specific mAbs from eachof the three groups defined here, as well as mAbs directed againstthe TCRß heterodimer, are all able to activate T cells.Therefore mAb attachment at several different sites on the TCR-CD3complex can give rise to activation signals. This suggests thatthe cross-linking function of mitogenic antibodies may be theirmost significant property, rather than the perturbation of aparticular ‘functional epitope’.     

High serum level of soluble CD30 in acute primary HIV-1 infection

CD30 has been suggested to play a role in HIV infection. In this study the serum concentration of soluble CD30 (sCD30) was determined by an ELISA essay on samples collected from patients with acute primary HIV-1 infection during the acute phase (n = 17) and after seroconversion (n = 13). sCD30 during acute infection was consistently elevated (137.58 ± 120.33 versus 6.4 ± 5.4 U/ml (mean ± s.d.) in normal controls; P < 0.0001) and decreased after seroconversion (49.1 ± 66.17 U/ml; P = 0.0018 compared with acute infection). This trend mirrored the disappearance of detectable levels of HIV antigen in the blood, resulting in a direct correlation between sCD30 and HIVAg values (P = 0.002). These data suggest that the high levels of sCD30 observed during the peak concentration of HIVAg in acute primary HIV infection might reflect the high rate of viral replication.     

Down-regulation of LFA-1-mediated T cell adhesion induced by the HIV envelope glycoprotein gp160 requires phosphatidylinositol-3-kinase activity

Human immunodeficiency virus binds to CD4⁺ T lymphocyte by the interaction, in part, between its gp120 envelope glycoprotein and the CD4 molecule. We and others have reported that the lipid kinase phosphatidylinositol-3-kinase (PI3-kinase) is associated with the CD4-p56^lck complex and can be activated by various CD4 ligands. In a previous report we showed that the gp160 envelope down-regulates lymphocyte function-associated antigen-1 (LFA-1)-dependent adhesion between CD4⁺ T cells and B cells. This down-regulation was shown to be p56^lck-dependent. Here we investigate the role of PI3-kinase in the inhibition of adhesion induced by gp160 binding to CD4. We found that gp160 activates the PI3-kinase of HUT78 CD4⁺ T cell lines in a way dependent on CD4-p56^lck association, since no activation was detected when the interaction between CD4 and p56^lck was disrupted. It was also shown, using different inhibitors of the PI3-kinase (wortmannin, Ly294002 and antisense oligonucleotides), that this lipid kinase was necessary for the down-regulation of LFA-1-mediated adhesion induced by gp160. These results strongly suggest that PI3-kinase activation induced by gp160 leads to down-regulation of LFA-1-mediated T cell adhesion to B cells. Inhibition by gp160 of cytoskeleton rearrangement-dependent, anti-CD3-mediated T cell adhesion to B cells was blocked by neutralization of PI3-kinase activity, while inhibition of cytoskeleton rearrangement-independent, Mg²⁺-induced T cell adhesion was not. These results emphasize the role of PI3-kinase in the regulation of cytoskeleton structure. It is proposed that gp160 activates both p56^lck and PI3-kinase which lead to a cytoskeleton organization unfavorable for LFA-1 function.     

Pharmacological evidence for stimulation of growth hormone secretion by a central noradrenergic system in dogs

The role of brain catecholamines in the regulation of growth hormone secretion was investigated in pentobarbital-anesthetized dogs by using drugs which modify the function of adrenergic neurons and receptors. Intravenous administration of L-dopa produced a prompt, statistically significant increase in plasma growth hormone concentration. This response was not significantly reduced by blockade of peripheral dopa decarboxylase activity with carbidopa. Clonidine, an alpha-agonist which penetrates the brain, increased plasma growth hormone secretion. Norepinephrine, epinephrine, dopamine and isoproterenol, catecholamines which do not penetrate the blood-brain barrier, failed to affect plasma growth hormone concentration when administered intravenously. Apomorphine did not produce a statistically significant increase in plasma growth hormone concentration when administered directly into the the third ventricle, and pimozide failed to abolish the increase in plasma growth hormone produced by L-dopa. The increase in plasma growth hormone concentration produced by intravenous L-dopa and clonidine was prevented by administration of phentolamine or phenoxybenzamine directly into the third ventricle. The response to L-dopa was also abolished by intraventricular procaine. In dogs in which central beta-adrenergic blockade was produced by intraventricular L-propranolol, the growth hormone response to L-dopa was greater than it was in control dogs treated with intraventricular D-propranolol. The data indicate that in pentobarbital anesthetized dogs, the increase in growth hormone secretion produced by L-dopa is mediated by norepinephrine, rather than dopamine, that the site of action of the norepinephrine is central, above the median eminence and inside the 'blood-brain barrier', and that the norepinephrine acts via alpha-adrenergic receptors.