Impaired T cell proliferation, increased soluble death-inducing receptors and activation-induced T cell death in patients undergoing haemodialysis

Haemodialysis is a widespread option for end-stage renal disease (ESRD). Long-term success of dialysis is, however, limited by a high rate of serious bacterial and viral infections. We compared T cell functions in ESRD patients undergoing haemodialysis (n = 20), or were not dialysed and received conventional medical treatment (n = 20). Healthy volunteers (n = 15) served as controls. The T cell phenotype was examined by immunofluorescence using fluorochrome-labelled monoclonal antibodies and FACS analysis. The concentration of soluble CD95/Fas and of tumour necrosis factor-alpha receptor type 1 (sTNFR1) in the sera was quantified by ELISA. Activation-induced programmed T cell death was triggered by anti-CD3/CD28 antibodies and measured by 7-AAD staining. All immunological tests were performed at least 1 month after dialysis initiation. T cell proliferation in response to phytohaemagglutinin or anti-CD3 monoclonal antibodies was moderately diminished in non-dialysed patients and markedly reduced in haemodialysis patients compared to healthy controls (P < 0.01 and P < 0.001, respectively). In a mixed lymphocyte culture the proliferative response of T cells from dialysed patients was significantly diminished (P < 0.001). T cells of both non-dialysed and dialysed patients have augmented CD95/Fas and CD45RO expression, increased sCD95/Fas and sTNFR1 release and spontaneously undergo apoptosis. Culture of T cells from haemodialysis patients with anti-CD3/CD28 antibodies increased the proportion of CD4(+) T cells committing activation-induced cell death by a mean 7.5-fold compared to T-helper cells from non-dialysed patients (P < 0.001). Renal failure and initiation of haemodialysis results in a reduced proliferative T cell response, an aberrant state of T cell activation and heightened susceptibility of CD4(+) T cells to activation-induced cell death.     

Theophylline disrupts diurnal rhythms of humoral factors with loss of meal cyclicity

To test the possibility that theophylline induced circadian disappearance of food intake might depend upon rhythmic disruption of blood glucose, insulin and free fatty acids (FFA), theophylline was administered chronically. This markedly lengthened postprandial intermeal intervals during the dark, and induced approximately identical intermeal intervals and identical meal sizes in the light and dark periods. In contrast to the clear light-dark dependent oscillations of serum glucose, insulin and FFA in the controls, the theophyllinized rats lost circadian fluctuation of each of these three chemical substances. Further, theophyllinized rats, unlike controls, had no time-dependent fluctuation in the levels of these substances at ? 120, ?60 or ?15 min preceding the onset of the first meal before the dark. These findings, together with previous reports, explain the disappearance of nocturnal feeding rhythm in theophyllinized rats in terms of functional destruction of circadian regulation in the hypothalamus which modulate the production of chemical determinants of food intake.     

Patterns of major histocompatibility complex class II expression by T cell subsets in different immunological compartments. 2. Altered expression and cell function following activation in vivo

This study characterizes antigen-induced phenotypic and functional aspects of major histocompatibility complex (MHC) class II expression on recirculating T cells in efferent lymph. In vivo secondary, but not primary challenge is associated with both kinetic and phenotypic alterations in class II expression by T cells. All three major T cell subsets, CD4⁺, CD8⁺ and T19⁺ (γδ T cell receptor), show an approximate four fold increase in the level of MHC class II expression during secondary responses. No changes in B cell expression of class II were seen. Resting efferent lymph T cells are predominantly either class II^? or DR⁺DQ^? but this changes to DR⁺DQ⁺ after antigenic challenge. The antigen-presenting function of these class II⁺ T cells was investigated at daily intervals after in vivo antigenic challenge. T cells from non-activated lymph nodes could not induce proliferation of antigen-specific T cells with soluble antigen but were weakly stimulatory in allo-mixed lymphocyte reaction (MLR) at high (> 2:1) stimulator cell ratios. Activated T cells isolated during secondary in vivo responses, and expressing increased quantities of MHC class II, were positive stimulator cells in the MLR. In contrast these cells could not present soluble antigen or trypsin-digested antigen to the T cell lines. In the MLR assays, the relative stimulation by class II⁺ T cells correlates with the levels of class II expression. We conclude from these experiments that both quantitative and qualitative changes in MHC class II, induced on T cells under physiological conditions, play a role in the regulation of the immune response in vivo but that that role is not simply one of presentation of soluble antigen.     

Intracellular Ca antagonist TMB-8 blocks catecholamine secretion evoked by caffeine and acetylcholine from perfused cat adrenal glands in the absence of extracellular Ca

Unlike acetylcholine, caffeine was much more effective in releasing catecholamine in the absence of extracellular Ca²⁺ than in its presence in perfused cat adrenal glands. The intracellular Ca²⁺ antagonist, TMB-8 (10⁻⁴ M), inhibited reversibly the catecholamine secretion evoked by caffeine (40 mM) and that induced by acetylcholine (10⁻⁴ M) in the presence of hexamethonium (10⁻³ M) during perfusion with Ca²⁺-free Locke solution containing EGTA (10⁻⁵ M). These results support our view that muscarinic receptor activation causes catecholamine secretion by mobilizing Ca²⁺ from an intracellular pool just as caffeine does.     

桑色素对小鼠T淋巴细胞体外活化、增殖和细胞周期的影响

目的:研究桑色素(morin)对小鼠T淋巴细胞活化、增殖和细胞周期的影响。方法:以刀豆蛋白A(ConA)刺激培养的淋巴结来源的小鼠淋巴细胞,再以不同终浓度的morin与T细胞共培养,利用流式细胞术(FCM),检测早期T细胞活化的标志CD69分子的表达,以羧基荧光素双醋酸盐琥珀酰脂(CFDA-SE)染色检测T细胞的增殖;以碘化丙锭(PI)染色分析T细胞的细胞周期。结果:小鼠T细胞培养6 h后,未经ConA刺激的对照组中CD69 T的细胞比率为(2.97±0.12)%,经ConA刺激的CD69 T细胞的比率明显增高,达到(72.52±0.66)%,与对照组相比差别明显(P<0.01)。终浓度为25、50、100μmol/L的morin均下调CD69 T细胞的比率,其中,100μmol/L的morin抑制作用最强,为(48.95±0.81)%,与对照组比较具有统计学意义(P<0.01)。CFDA-SE染色分析显示,ConA组培养48 h和72 h的T细胞的增殖指数(PI)分别为(1.58±0.04)和(1.95±0.02),各浓度的morin对ConA刺激的T细胞增殖,具有明显地抑制作用,以100μmol/L的morin抑制作用最明显。培养48 h的ConA组T细胞的PI为(1.02±0.02)、培养72 h的ConA组T细胞的PI为(1.03±0.01),与相应时间的对照组比较,均有统计学意义(P<0.01)。PI染色后流式细胞术分析的结果表明,ConA组处于S期的T细胞的比率为(27.05±0.39)%,显著高于对照组的比率(5.10±0.07)%。morin组中S期的细胞比率较高。结论:Morin可显著抑制ConA刺激的T细胞活化及增殖;其对增殖的抑制作用主要表现为S期的细胞的阻滞。     

视黄醇结合蛋白4与代谢综合征的关系

目的 探讨视黄醇结合蛋白4(RBP4)的血清水平及-G 803 A SNP与代谢综合征的关系.方法 收集116名伴2型糖尿病的代谢综合征患者和93名正常体检者,放射免疫法测定RBP4血清水平,聚合酶链式反应及序列分析检测G 803 A多态性基因型.结果 (1)RBP4水平在所有受试者中与体质指数(BMI)、腰围、空腹胰岛素(FINS)、胰岛素抵抗指数(HOMA-IR)、三酰甘油(TG)正相关,对照组中与TG、TC、LDL-C正相关,男性组中与DBP正相关,女性组中与年龄、FINS、HOMA-IR、TG、SBP正相关,多元逐步回归分析发现腰围、BMI、TG和年龄是独立相关因素;RBP4水平在代谢综合征组和男性组显著升高,在有规律运动组显著降低.(2)代谢综合征组与正常对照组的RBP4-G 803 A多态性基因型分布未见显著差异,按不同基因型分组的代谢指标亦无显著性差异.结论 在中国汉族人群中,RBP4水平与多个代谢参数相关,RBP4基因-G 803 A SNP与代谢综合征没有关联.     

Changes in electromyographic activity,muscle fibre and force production characteristics during heavy resistance/power strength training in middle‐aged and older men and women

The effects of a 6‐month resistance training (2 day/week) designed to develop both strength and power on neural activation by electromyographic activity (EMG) of the agonist and antagonist knee extensors, muscle fibre proportion and areas of type I, IIa, and IIb of the vastus lateralis (VL) as well as maximal concentric one repetition maximum (1 RM) strength and maximal and explosive isometric strength of the knee extensors were examined. A total of 10 middle‐aged men (M40; 42 ± 2), 11 middle‐aged women (W40; 39 ± 3), 11 elderly men (M70; 72 ± 3) and 10 elderly women (W70; 67 ± 3) served as subjects. Maximal and explosive strength values remained unaltered during a 1‐month control period. After the 6‐month training maximal isometric and 1RM strength values increased in M40 by 28 ± 14 and 27 ± 7% (P < 0.001), in M70 by 27 ± 17 and 21 ± 9% (P < 0.001), in W40 by 27 ± 19 and 35 ± 14% (P < 0.001) and in W70 by 26 ± 14 and 31 ± 14% (P < 0.001), respectively. Explosive strength improved in M40 by 21 ± 41% (P < 0.05), in M70 by 21 ± 24% (P < 0.05), in W40 by 32 ± 45% (NS) and in W70 by 22 ± 28% (P < 0.05). The iEMGs of the VL and vastus medialis (VM) muscles increased during the training in M40 (P < 0.001 and 0.05), in M70 (P < 0.001 and 0.05), in W40 (P < 0.001 and 0.05) and in W70 (P < 0.001 and 0.05). The antagonist biceps femoris (BF) activity during the isometric knee extension remained unaltered in M40, in W40, and in M70 but decreased in W70 (from 42 ± 34 to 32 ± 26%; P < 0.05) during the first 2 months of training. Significant increases occurred during the training in the mean fibre areas of type I in W70 (P < 0.05) and of overall type II along with a specific increase in IIa in both W40 (P < 0.05) and in W70 (P < 0.05), while the changes in the male groups were not statistically significant. The individual percentage values for type II fibres at pretraining correlated with the individual values for 1 RM strength in both W70 (r=0.80; P < 0.05) and M70 (r=0.61; P < 0.05) and also at post‐training for maximal isometric torque in W70 (r=0.77, P < 0.05). The findings support the concept of the important role of neural adaptations in strength and power development in middle‐aged and older men and women. The muscle fibre distribution (percentage type II fibres) seems to be an important contributor on muscle strength in older people, especially older women. Women of both age groups appear to be hypertrophically responsive to the total body strength training protocol performed two times a week including heavier and lower (for fast movements) loads designed for both maximal strength and power development, while such a programme has limited effects on muscle hypertrophy in men.     

Expression of early activation antigen (CD69) during human thymic development.

The novel early activation antigen, EA1, has been shown to be induced by mitogens, antigens and the tumour promoter, phorbol myristate acetate (PMA), on human lymphocytes. This antigen has been designated to be CD69. EA1 has also been shown to be expressed on thymocytes without exogenous activation stimuli. In order to characterize further the expression of EA1 on thymocytes, the ontogeny of its expression was studied. EA1 appeared between 7 and 9.5 weeks of gestation, after colonization of the thymic rudiment with CD7+ T cell precursors, but before the onset of compartmentalization of the thymus into cortical and medullary zones. After cortico-medullary differentiation, the majority of medullary thymocytes expressed EA1 while only a fraction of the cortical thymocytes expressed this antigen. In the fetal and post-natal cortex, EA1 expression appeared to cluster in the subcapsular cortex. EA1+ cells were also scattered throughout the inner cortex. By two-colour fluorocytometric analysis of post-natal thymocytes, it was shown that EA1 was expressed on 30 to 65% of thymocytes. EA1 was expressed on CD4+ CD8+ as well as on the more immature CD4- CD8- thymocytes. In contrast to circulating T cells, thymocytes were much less responsive to PMA stimulation for the expression of EA1. Molecular characterization showed that EA1 on thymocytes had the same structure as that of activated peripheral T cells. In addition, thymic EA1 was constitutively phosphorylated. Thus, EA1 expression is acquired early during thymic development after colonization of the thymic rudiment by CD7+ T cell precursors. However, the specific role that EA1 may play in the activation and function of developing thymocytes remains to be determined.     

Activation of the immune system of cancer patients by continuous i.v. recombinant IL-2 (rIL-2) therapy is dependent on dose and schedule of rIL-2.

The effect of dose and schedule of continuous i.v. rIL-2 infusions on leucocyte subset counts, activation status of CD56+CD3- natural killer (NK) and CD3+ T lymphocytes, and cytolytic activities of peripheral blood mononuclear cells (PBMC) was studied. A single 4-day course of rIL-2 in escalating doses (0.9-11.5 x 10(6) U/m2 per day) was given to 18 patients with various types of metastatic cancer. The serum IL-2 concentration during rIL-2 therapy ranged between 23 and 64 U/ml and was proportional to the administered rIL-2 dose, as was the rebound lymphocytosis following therapy. Before therapy, the CD56+CD3- NK cells expressed low levels of the p75 chain of the IL-2 receptor (IL-2R) and virtually no IL-2R(p55). Most CD3+ T cells were IL-2R(p55-,p75-). Between 2 and 4 days following therapy, i.e. at the time of lymphocytosis, the percentage of CD56+,CD3- NK cells among the lymphocytes had increased proportional to the administered rIL-2 dose. The levels of IL-2R(p75) expression by the CD56+,CD3- NK cells had increased. The percentages of CD3+ T cells expressing IL-2R(p55), HLA-DR and CD45RO had increased proportional to the administered rIL-2 dose. The level of lymphokine- activated killer (LAK) activity against Daudi cells was also positively correlated with rIL-2 dose. Subsequently, seven patients received 4-weekly cycles of rIL-2 (2.9-4.4 x 10(6) U/m2 per day) during 4 consecutive weeks. This schedule led to marked increments in lymphocyte and eosinophil counts, and to increased cytolytic activities compared with pretreatment. We conclude that CD56+,CD3- NK and CD3+ T cells are activated differentially by continuous i.v. rIL-2 proportional to dose and duration of treatment.