Age-dependent changes in T cell homeostasis and SIV load in sooty mangabeys

Sooty mangabeys ( Cercocebus atys ) showed age-dependent changes in T cell regeneration. Younger animals had a high percentage of CD4+ CD45RA+ T cells and a high concentration of T cell receptor excisional circles (TRECs) in peripheral blood, which indicated active thymopoiesis. In contrast, older animals had an increased T cell turnover, which suggested that most T cell production occurred in the periphery. In addition, the number of peripheral CD4+ T cells naturally decreased with age. Non-pathogenic SIVsm infection did not significantly change the T cell proliferation rate or the TREC concentration, though it did cause a moderate loss of peripheral CD4+ T cells. The viral load correlated negatively with age, which could be accounted for by the reduced availability of CD4+ target cells in older mangabeys. Thus, the number of susceptible target cells may be a limiting factor in natural SIV infection.     

Ability of CD8(+) T cell anti-feline immunodeficiency virus activity correlated with peripheral CD4(+) T cell counts and plasma viremia

In the host defense mechanism against feline immunodeficiency virus (FIV) infection, CD8(+) T cells specifically attack virus-infected cells and suppress the replication of the virus in a non-cytolytic manner by secreting soluble factors. In this study, we measured CD8(+) T cell anti-FIV activity in 30 FIV-infected cats. We investigated its relationship with the number of peripheral blood lymphocytes, particularly the CD4(+) T cell and CD8(+) T cell counts, and the relationship between anti-FIV activity and the number of T cells of CD8alpha(+)beta(lo) and CD8alpha(+)beta(-) phenotypes. A clearly significant correlation was observed between anti-FIV activity and the number of CD4(+) T cells. A weaker anti-FIV activity was associated with a greater decrease in the number of CD4(+) T cells. However, there was no significant correlation between anti-FIV activity and the number of B or CD8(+) T cells. Compared with SPF cats, FIV-infected cats had significantly higher CD8alpha(+)beta(lo) T cell and CD8alpha(+)beta(-) T cell counts, but, no significant correlation was observed between these cell counts and anti-FIV activity. This anti-FIV activity significantly correlated with plasma viremia, which was detected in cats with a weak anti-FIV activity. These results suggest that the anti-FIV activity of CD8(+) T cells plays an important role in plasma viremia and the maintenance of CD4(+) T cells in the body. It is unlikely that CD8alpha(+)beta(lo) or CD8alpha(+)beta(-) T cells appearing after FIV infection represent a phenotype of CD8(+) cells with anti-FIV activity.     

Systemic vaccination prevents the total destruction of mucosal CD4 T cells during acute SIV challenge

BACKGROUND: Acute human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) infections are accompanied by a systemic loss of memory CD4 T cells, with mucosal sites serving as a major site for viral replication, dissemination and CD4 T cell depletion. Protecting the mucosal CD4 T cell compartment thus is critical to contain HIV, and preserve the integrity of the mucosal immune system. The primary objective of this study was to determine if systemic vaccination with DNA/rAd-5 encoding SIV-mac239-env, gag and pol could prevent the destruction of CD4 T cells in mucosal tissues. METHODS: Rhesus macaques were immunized with DNA/r-Ad-5 encoding SIV genes and compared with those immunized with sham vectors following high dose intravenous challenge with SIVmac251. SIV specific CD4 and CD8 T cell responses, cell associated viral loads and mucosal CD4 T cell dynamics were evaluated. RESULTS: Strong SIV specific immune responses were induced in mucosal tissues of vaccinated animals as compared with sham controls. These responses expanded rapidly following challenge suggesting a strong anamnestic response. Immune responses were associated with a decrease in cell associated viral loads, and a loss of fewer mucosal CD4 T cells. Approximately 25% of mucosal CD4 T cells were preserved in vaccinated animals as compared with <5% in sham controls. These results demonstrate that systemic immunization strategies can induce immune responses in mucosal tissues that can protect mucosal CD4 T cells from complete destruction following challenge. CONCLUSIONS: Preservation of mucosal CD4 T cells can contribute to maintaining immune competence in mucosal tissues and provide a substantial immune benefit to the vaccinees.     

HIV/AIDS患者机会性感染与CD4+ T淋巴细胞间的关联性

目的 研究人免疫缺陷病毒（HIV）感染者及艾滋病（AIDS）患者发生机会性感染的概率与自身CD4+ T淋巴细胞之间的关系,为HIV患者机会性感染的防治提供参考。方法 以2016年6月至2017年6月我院400例HIV患者为研究对象,回顾性分析不同CD4+T淋巴细胞计数HIV患者发生机会性感染的情况。结果 400例HIV患者发生机会性感染178例,总感染率为44.5%。CD4+T淋巴细胞计数≤50个/μL的患者机会性感染发生率（86.67%）最高,与其他各组比较差异有统计学意义（P<0.05）。随着CD4+ T淋巴细胞计数的减少,HIV患者机会性感染率升高。178例机会性感染者中,单一感染82例,2部位感染52例,3部位感染28例,4部位以上感染16例。感染病原体检测显示,细菌感染84例（47.19%）,结核杆菌感染36例（20.22%）,病毒感染30例（16.85%,包括巨细胞病毒感染18例、单纯疱疹病毒感染12例）,真菌感染77例（43.25%,包括假丝酵母感染35例,肺孢子菌感染20例,马尔尼菲青霉菌感染12例,新型隐球菌感染10例）,未明确病原体性质34例（19.10%）,复合感染多见。结论 CD4+ T淋巴细胞水平与HIV患者继发机会性感染的概率关系密切。HIV患者CD4+ T淋巴细胞水平的监测对其继发机会性感染的防控具有重要临床意义。     

Vaccination with SIVmac239Δnef activates CD4+ T cells in the absence of CD4+ T-cell loss

Background  Pathogenic HIV and SIV infections characteristically deplete central memory CD4⁺ T cells and induce chronic immune activation, but it is controversial whether this also occurs after vaccination with attenuated SIVs and whether depletion or activation of CD4⁺ T-cell play roles in protection against wild-type virus challenge.
Methods  Rhesus macaques were vaccinated with SIVmac239Δnef and quantitative and phenotypic polychromatic flow cytometry analyses were performed on mononuclear cells from blood, lymph nodes and rectal biopsies.
Results  Animals vaccinated with SIVmac239Δnef demonstrated no loss of CD4⁺ T cells in any tissue, and in fact CCR5⁺ and CD28⁺CD95⁺ central memory CD4⁺ T cells were significantly increased. In contrast, CD4⁺ T-cell numbers and CCR5 expression significantly declined in unvaccinated controls challenged with SIVmac239. Also, intracellular Ki67 increased acutely as much as 3-fold over baseline in all tissues after SIVmac239Δnef vaccination then declined following primary infection.
Conclusion  We demonstrated in this study that SIVmac239Δnef vaccination did not deplete CD4⁺ T cells but transiently activated and expanded the memory cell population. However, increases in numbers and activation of memory CD4⁺ T cells did not appear to influence protective immunity.     

Use of human CD3 monoclonal antibody for accurate CD4+ and CD8+ lymphocyte determinations in macaques: phenotypic characterization of the CD3- CD8+ cell subset

Macaque monkeys are frequently used in models for studies of infectious diseases, immunity, transplantation and vaccine development. Such use is largely due to the conservation of functionally important cell surface molecules and the phylogenetic proximity of their immune systems to that of humans. Some monoclonal antibodies (mAb) raised against human leukocyte antigens can be utilized in the monkey. Until recently, many primate centers have utilized the CD2 monoclonal antibody to enumerate T lymphocytes. We have evaluated the anti-human CD3 mAb in macaques and sooty mangabeys. Using this monoclonal antibody, pigtailed macaques were found to have a much higher proportion of CD2+ CD3- CD8+ cells as compared with rhesus macaques and sooty mangabeys. Such cells comprised approximately one-half of all CD8+ cells in the pigtailed macaque, but only one-quarter of CD8+ cells in the rhesus, and one-fifth in the sooty mangabey. Use of the CD2 monoclonal antibody as the T-cell marker resulted in underestimating CD4/CD8 ratios compared with using the CD3 mAb in pigtailed macaques. Phenotypic characterization of this subset of CD3- CD8+ cells indicated that they are CD16+, CD45RA+, CD11b+, CD69+ and CD28-. This would indicate that these cells represent an activated natural killer cell subset.     

Presence of a helix in human CD4 cytoplasmic domain promotes binding to HIV-1 Nef protein

The Nef proteins of simian and human immunodeficiency viruses are known to directly bind and downregulate the CD4 receptor of infected cells. Recent results suggest that residues forming an alpha-helix N-cap in the CD4 cytoplasmic domain play a role in binding of CD4 to human immunodeficiency virus type 1 Nef protein. We determined the dissociation constants between Nef and several CD4 peptides that contain or do not contain the respective alpha-helix N-cap. Further, we compared helical secondary structure content of these CD4 peptide variants by circular dichroism spectroscopy. We conclude that presence of an alpha-helix in CD4 cytoplasmic domain increases CD4 affinity to Nef. In addition, the amino acid sequence of residues forming the helix N-cap influences CD4 affinity to Nef, too. Finally, the structural changes induced in Nef and CD4 upon binding to each other are investigated.     

应用流式细胞术分析林麝外周血 CD4+、CD8+ T淋巴细胞

通过对圈养林麝(Moschusberezovskii)外周血淋巴细胞CD4~+、CD8~+亚群的检测,探讨林麝细胞免疫功能状态,并探索应用流式细胞仪分析其淋巴细胞亚群的方法,为研究林麝重大疾病的病理机制及诊断方法提供科学依据。本研究选取健康林麝和患呼吸道疾病林麝各5头,以双色流式细胞术检测其外周血淋巴细胞CD4~+、CD8~+亚群的含量,并进行比较。结果显示,羊源CD4、CD8的流式荧光抗体能够标记林麝细胞并有效检测;患病林麝与健康林麝相比,外周血CD4~+细胞含量无差异(P 0.05),CD8~+细胞含量则显著降低(P 0.01),CD4~+/CD8~+比值显著增高(P 0.01)。结果表明,患呼吸系统炎性疾病的林麝其外周血淋巴细胞CD8~+亚群变化显著,检测淋巴细胞亚群对林麝疾病的诊断有重要意义。     

Heterogeneity in phenotype and function of CD8+ and CD4/CD8 double‐negative Natural Killer T cell subsets in sooty mangabeys

Background We have recently reported the presence of CD8⁺ and CD4/8 double‐negative (DN) natural killer T (NKT) lymphocytes in sooty mangabeys. To investigate differences in the two NKT cell subsets, we compared the phenotype and function of sooty mangabey CD8⁺ and DN NKT cells. Methods Flow‐sorted NKT lymphocytes from one SIV‐negative sooty mangabey were subjected to limiting dilution cloning. Invariant NKT clones were characterized by flow cytometry and cytokine ELISA. Results The majority of NKT clones displayed an effector memory phenotype and expressed CXCR3 and NKG2D. While CD8⁺ NKT subsets expressed significantly higher levels of granzyme B and perforin and produced more IFN‐γ, the DN NKT subsets secreted significantly more IL‐4, IL‐13, and IL‐10. Conclusions The Th1 and Th2 cytokine bias of CD8⁺ and DN NKT cells, respectively, indicates the presence of functionally heterogeneous populations of NKT cells in sooty mangabeys.     

Novel role of aquaporin-4 in CD4+ CD25+ T regulatory cell development and severity of Parkinson's disease

Aquaporin-4 (AQP4) is highly expressed in mammalian brains and is involved in the pathophysiology of cerebral disorders, including stroke, tumors, infections, hydrocephalus, epilepsy, and traumatic brain injury. We found that AQP4-deficient mice were hypersensitive to stimulations such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or lipopolysaccharide compared to wild-type (WT) littermates. In a mouse model of MPTP-induced Parkinson's disease (PD), AQP4-deficient animals show more robust microglial inflammatory responses and more severe loss of dopaminergic neurons (DNs) compared with WT mice. However, a few studies have investigated the association of abnormal AQP4 levels with immune dysfunction. Here, for the first time, we report AQP4 expression in mouse thymus, spleen, and lymph nodes. Furthermore, the significantly lower numbers of CD4(+) CD25(+) regulatory T cells in AQP4-deficient mice compared to WT mice, perhaps resulting from impaired thymic generation, may be responsible for the uncontrolled microglial inflammatory responses and subsequent severe loss of DNs in the substantia nigra pars compacta in the MPTP-induced PD model. These novel findings suggest that AQP4 deficiency may disrupt immunosuppressive regulators, resulting in hyperactive immune responses and potentially contributing to the increased severity of PD or other immune-associated diseases.     

CD4+CD25+FoxP3+ 调节性T 细胞与黑龙江省HIV/AIDS 患者病情 相关性的研究

目的:比较黑龙江省HIV/AIDS患者与健康对照者(healthy controls,HCs)外周血CD4+CD25+FoxP3+调节性T细胞数量、免疫抑制功能的变化,探讨CD4+CD25+FoxP3+调节性T细胞在HIV/AIDS感染过程中的作用。方法:采用流式细胞仪检测21例HIV/AIDS患者及20例健康对照组的外周血CD4+CD25+FoxP3+调节性T细胞数量的百分比及绝对数量;采用共同培养方法检测HIV/AIDS患者外周血CD4+CD25+FoxP3+调节性T细胞免疫抑制功能的变化;实时荧光定量聚合酶链反应(RT-FQ-PCR)检测HIV/AIDS患者外周血CD4+CD25+FoxP3+调节性T细胞中FoxP3mRNA的表达。结果:黑龙江省HIV/AIDS患者外周血CD4+CD25+FoxP3+调节性T细胞比率明显高于HCs(P<0.01),而CD4+CD25+FoxP3+调节性T细胞的绝对计数显著下降,且与CD4+T细胞绝对计数成反比;混合淋巴细胞共同培养结果显示,HIV/AIDS患者外周血CD4+CD25+FoxP3+调节性T细胞的抑制功能无明显变化;HIV/AIDS患者外周血CD4+CD25+FoxP3+调节性T细胞的FoxP3 mRNA相对表达量无显著变化。结论:黑龙江省HIV/AIDS患者CD4+CD25+FoxP3+调节性T细胞的数量变化与病情相关。     

rhG-CSF 动员对供者CD4+ T 细胞免疫表型和功能影响

目的:研究重组人粒细胞集落刺激因子(rhG-CSF)动员对供者CD4+T细胞表面分子淋巴细胞功能相关抗原-1(LFA-1)、细胞间黏附分子-1(ICAM-1)、L-选择素(LAM-1)和人整合素-4(VLA-4)的表达及其介导的CD4+T细胞功能的影响,探讨外周血干细胞移植过程中CD4+T细胞免疫耐受机制。方法:使用三色荧光标记检测动员前及动员后第5天供者外周血LFA-1、ICAM-1、LAM-1和VLA-4的表达率,ELISA方法检测动员前后CD4+T细胞分泌IFN-γ和IL-4能力,免疫磁性分选法分离纯化CD4+T细胞,检测动员前后CD4+T细胞对基质细胞衍生因子-1α(SDF-1α)的迁移能力和对ICAM-1的黏附能力。结果:动员前后CD4+T细胞LFA-1(CD11a)和VLA-4(CD49d)表达率差异无统计学意义(P>0.01),动员前后CD4+T细胞LAM-1(CD62L)和ICAM-1(CD54)的表达率差异均有统计学意义,动员前显著高于动员后(P<0.01);动员前后CD4+T淋巴细胞向SDF-1α的迁移率差异无统计学意义(P>0.01);动员后CD4+T细胞对ICAM-1的黏附率降低(P<0.01);动员后IL-4和IFN-γ两个细胞因子在外周血血清的浓度均降低(P<0.01)。结论:rhG-CSF动员不影响CD4+T细胞LFA-1和VLA-4表达及CD4+T细胞迁移,但影响CD4+T细胞ICAM-1和LAM-1表达以及CD4+T细胞通过LFA-1对ICAM-1的黏附能力影响,并可能影响CD4+T细胞分泌细胞因子IL-4及IFN-γ的功能。     

T cell receptor repertoire of CD4+ and CD8+ T cell subsets in the allogeneic bone marrow transplant recipient

Allogeneic bone marrow transplantation (BMT) has become a therapy of choice for the treatment of certain malignancies and hematopoietic disorders. However, immunodeficiencies following BMT continue to cause significant morbidity and mortality. We have compared the T cell receptor (TCR) repertoire of BMT patients and healthy control individuals by staining peripheral blood mononuclear cells with fluorochrome-labeled TCR-specific antibodies. Several patients exhibited a biased pattern of TCR expression atypical of the healthy controls, yet no particular TCR bias characterized all patients. For example, we found that 2%–8% of T cell from healthy individuals expressed the V19 TCR. One BMT patient exhibited V19 expression on more than 60% of peripheral T cells, while additional patients expressed V19 on less than 1% of T cells. The patients with the most extreme skewing of TCR types suffered from graft-versus-host disease. The causes of skewed TCR V expression patterns in BMT patients are not fully understood, yet some researchers have suggested that an oligoclonal expansion of CD8⁺ T cell populations may be largely responsible. To test this hypothesis, we examined the TCR V repertoire of CD4⁺ and CD8⁺ T cell populations. We found that biased V expression characterized both CD4⁺ and CD8⁺ T cell populations, sometimes within a single individual. Thus, therapies directed toward CD8⁺ T cells alone may not fully correct repertoire abnormalities following BMT.     

The role of virus-specific CD4+ T cells in the control of Epstein-Barr virus infection

Epstein-Barr virus (EBV) establishes lifelong persistent infections in humans and has been implicated in the pathogenesis of several human malignancies. Protective immunity against EBV is mediated by T cells, as indicated by an increased incidence of EBV-associated malignancies in immunocompromised patients, and by the successful treatment of EBV-associated post-transplant lymphoproliferative disease (PTLD) in transplant recipients by the infusion of polyclonal EBV-specific T cell lines. To implement this treatment modality as a conventional therapeutic option, and to extend this protocol to other EBV-associated diseases, generic and more direct approaches for the generation of EBV-specific T cell lines enriched in disease-relevant specificities need to be developed. To this aim, we studied the poorly defined EBV-specific CD4+ T cell response during acute and chronic infection.     

Differential requirements for proliferation of CD4+ and gammadelta+ T cells to spirochetal antigens

Alphabeta+ and gammadelta+ T cells have different mechanisms of epitope recognition and are stimulated by antigens of different chemical nature. An immunization model with antigens from the spirochete Brachyspira hyodysenteriae was used to examine the requirements for proliferation of circulating porcine CD4+ and gammadelta+ T cells in mixed lymphocyte cultures. CD4+ T cells only responded to stimulation with B. hyodysenteriae antigens, whereas gammadelta+ T cells proliferated when cultures were stimulated with either spirochetal antigens or interleukin-2 (IL-2). T cells that had proliferated expressed high levels of IL-2-receptor-alpha (IL-2Ralpha). Furthermore, neutralization of IL-2 at the beginning of the culture period was more efficient in blocking gammadelta+ than CD4+ T cell proliferation. Immunization induced interferon-gamma (IFN-gamma) production by CD4+ T cells, whereas only a small fraction of the antigen-stimulated gammadelta+ T cells produced this cytokine. Our results indicate that, under the same environmental conditions, CD4+ T cell functions are more tightly regulated when compared to gammadelta+ T cells. We conclude that these differences are due, in part, to the enhanced gammadelta+ T cell responsiveness to IL-2.     

Blocking of CD4 cell receptors for the human immunodeficiency virus type 1 (HIV-1) by chemically modified bovine milk proteins: Potential for AIDS prophylaxis

The chemical transformation of synthetic combinatorial libraries to increase the diversity of compounds of medicinal interest was reported recently. Chemical modification of natural products represents a complementary approach to accomplish this aim. Modification of lysines by aromatic acid anhydrides, preferentially by 3-hydroxyphthalic and trimellitic anhydrides and trimellitic anhydride chloride, converted commonly available proteins (human and bovine serum albumin and casein) into potent inhibitors of (i) binding between the HIV-1 gp120 envelope glycoprotein and the CD4 cell receptor, probably owing to their binding to CD4, and (ii) infection by HIV-1. Modified bovind milk proteins are also potent HIV-1 inhibitors and may have protential for anti-Hiv-1 prophylaxis.