Effect of phorbol myristate acetate on T cell colony formation, interleukin-2 (IL-2) receptor expression and IL-2 production by cells from patients at all stages of HIV infection.

We and others have shown that several T cell responses induced by the mitogen phytohaemagglutinin (PHA), including T cell colony formation, IL-2 receptor (IL-2R) expression, and IL-2 production are impaired in patients with AIDS and lymphadenopathy syndrome (LAS). We investigated whether phorbol myristate acetate (PMA) could act in synergy with PHA (as it does in healthy subjects) to enhance in vitro T cell responses of patients at all stages of infection by HIV. In AIDS patients with opportunistic infections (AIDS/OI), PHA + IL-2 + PMA led to a total disappearance of T cell colonies in 10/11 patients, among whom six already displayed very low numbers of colonies induced by PHA + IL-2 (less than 50 colonies/5 x 10(4) cells). In contrast, T cell colony formation induced by PHA + IL-2 + PMA was maintained or increased, compared with that induced by PHA + IL-2, in five out of six AIDS patients with Kaposi's sarcoma (AIDS/KS), 10/14 LAS and six out of seven HIV-seropositive asymptomatic (HIV+/AS) homosexuals. In these three groups of patients, a low percentage of colony cells induced by PHA + IL-2 + PMA expressed CD3 and CD4 molecules, but 50-89% of cells were IL-2R (Tac) positive, as in healthy controls. Studies on T cell activation and IL-2 production were performed on a selected group of 12 HIV-infected patients for whom sufficient numbers of lymphocytes could be obtained. PMA induced CD4 down-modulation in controls and in HIV-infected patients. However, CD3 down-modulation and induction of the Tac chain of IL-2R by PMA were significantly impaired in patients, compared with controls, and these two parameters were correlated. Although PHA alone induced virtually normal levels of Tac antigen on patients' cells, Tac induction by PHA + PMA was significantly decreased in patients versus controls. Cells from five out of 10 patients tested failed to produce detectable amounts of IL-2 after PHA stimulation, whereas IL-2 production increased significantly in all patients tested (n = 9) after PHA + PMA, with a level of IL-2 activity significantly higher than in controls. No correlation was found in this group of patients between the effects of PMA + PHA on T cell colony formation, Tac expression, or IL-2 production, as compared with PHA alone. Taken together, our results indicate that in vitro T cell functional studies with PMA may be useful to evaluate better the defects of T cell activation in HIV-infected patients.     

T lymphocyte anergy during acute infectious mononucleosis is restricted to the clonotypic receptor activation pathway.

The transient T cell anergy associated with acute infectious mononucleosis (IM) caused by the Epstein-Barr virus has been analysed in a sample of 14 IM children. Peripheral blood mononuclear cells (PBMC) obtained from IM patients showed a significant specific impairment in their proliferative response to both phytohaemagglutinin (PHA; P less than 0.05) and to an anti-CD3 MoAb (P less than 0.001), although both responses reached normal control levels by addition of a submitogenic dose of either phorbol myristate acetate (PMA) or recombinant IL-2 (rIL-2). In contrast, activation signals delivered through other surface molecules (CD2, CD28) or other transmembrane pathways (PMA plus a calcium ionophore) elicited normal or high proliferative responses in most IM PBMC. In a group of five patients tested, the synthesis of IL-2 by IM PBMC in the presence of PMA was impaired when PHA or anti-CD3 was used as stimulus, but it reached normal levels with anti-CD2 or ionophore. Lastly, PHA failed to induce IL-2 alpha receptor (IL-2R alpha) expression in IM PBMC from four tested patients, but the presence of PMA completely corrected this defect. Taken together, these results strongly suggest that the T cell anergy associated with acute IM is due to a T cell receptor (TCR)-specific impairment in the induction of genes involved in T cell proliferation (including those coding for IL-2 and IL-2R alpha) upon membrane signalling to otherwise normal T lymphocytes, since CD2, CD28 and certain transmembrane activation pathways are uncoupled from CD3 in these particular pathological conditions (and perhaps in most in vivo situations). This and other similar experimental approaches to transient secondary immunodeficiencies may help to unravel the physiopathological role of different surface molecules in T cell activation.     

CD28 activation promotes Th2 subset differentiation by human CD4+ cells

Ligation of CD28 provides a costimulatory signal to T cells necessary for their activation resulting in increased interleukin (IL)-2 production in vitro, but its role in IL-4 and other cytokine production and functional differentiation of T helper (Th) cells remains uncertain. We studied the pattern of cytokine production by highly purified human adult and neonatal CD4⁺ T cells activated with anti-CD3, phorbol 12-myristate 13-acetate (PMA) and ionomycin, or phytohemagglutinin (PHA) in the presence or absence of anti-CD28 in repetitive stimulation-rest cycles. Initial stimulation of CD4⁺ cells with anti-CD3 (or the mitogens PHA or PMA+ionomycin) and anti-CD28 monoclonal antibodies induced IL-4, IL-5 and interferon-γ (IFN-γ) production and augmented IL-2 production (6- to 11-fold) compared to cells stimulated with anti-CD3 or mitogen alone. The anti-CD28-induced cytokine production corresponded with augmented IL-4 and IL-5 mRNA levels suggesting increased gene expression and/or mRNA stabilization. Most striking, however, was the progressively enhanced IL-4 and IL-5 production and diminished IL-2 and IFN-γ production with repetitive consecutive cycles of CD28 stimulation. The enhanced Th2-like response correlated with an increased frequency of IL-4-secreting cells; up to 70% of the cells produced IL-4 on the third round of stimulation compared to only 5% after the first stimulation as determined by ELISPOT. CD28 activation also promoted a Th2 response in naive neonatal CD4⁺ cells, indicating that Th cells are induced to express a Th2 response rather than preferential expansion of already established Th2-type cells. This CD28-mediated response was IL-4 independent, since enhanced IL-5 production with repetitive stimulation cycles was not affected in the presence of neutralizing anti-IL-4 antibodies. These results indicate that CD28 activation may play an important role in the differentiation of the Th2 subset in humans.     

Selective loss of T cell functions in different stages of HIV infection Early loss ofanti-CD3-induced T cell proliferation followed by decreased anti-CD3-induced cytotoxic T lymphocyte generation in AIDS-related complex and AIDS

To investigate the effects of persistant human immunodeficiency virus (HIV) infectionon T cell reactivity, functional properties of peripheral blood T cells from HIV-seropositive homosexual men in various stages of infection were studied. T cell activationvia CD3 resulting in proliferation and differentiation was measured in a model system independent of accessory cells, using immobilized anti-CD3 monoclonal antibodies (mAb). T cells from HIV-infected asymptomatic men had a decreased proliferative response compared to HIV-negative controls. T cells from AIDS-related complex (ARC) and AIDS patients, compared to T cells from asymptomatic HIV-infected men, had a significantly lower proliferative response to anti-CD3 mAb. This diminished response to anti-CD3 mAb was shown to be due to decreased interleukin (IL)2 productionand could be enhanced by co-stimulation with anti-CD28 mAb or by adding IL2. Anti-CD3-induced generation of cytotoxic T lymphocytes was fully intact in early infection but was severely decreased in T cells from ARC and AIDS patients. Cytotoxic activity could be restored to near normal levels after co-stimulation with either anti-CD28 mAb or IL2. Our data demonstrate a differential loss of T cell functions in the course of HIV infection which is predominantly caused by a lack of IL2 production after stimulation via the CD3/T cell receptor complex. In early HIV infection this seems to be predominantly caused by a specific loss of memory T cells. However, in later stages of infection when both naive and memory T cell subsets are depleted, resultingin a normal naive/memory T cell ratio, T cell functions further deteriorate probably due to intrinsic activation defects. These findings may be of pathogenic relevance since diminished T cell reactivity may facilitate spreading and replication of virulent HIV variants heralding development of ARC and AIDS.     

Human Naive and Memory T-Helper Cells Display Distinct Adhesion Properties to ICAM-1, LFA-3 and B7 Molecules

In this paper the contribution of different accessory molecules to the adhesion of resting, naive and memory CD4⁺ T cells was examined utilizing a panel of CHO cell transfectants as model antigen-presenting cells (APCs). CD4⁺ T lymphocytes demonstrated strong adhesion to HLA-DR4 transfected CHO cells co-expressing B7, ICAM-I or LFA-3 molecules, suggesting that all three adhesion pathways is utilized by resting CD4⁺ cells. Monoclonal antibodies (MoAbs) against the corresponding receptors on T cells, e.g. anti-CD28, anti-LFA-1β and anti-CD2, inhibited completely T-cell adhesion to natural ligands expressed on transfected CHOcells. Pretreatment of CD4⁺ T cells with NKI-L16 MoAb, which interact with an activation epitope on LFA-loc chain, enhanced adhesion to ICAM-1 but not B7 or LFA-3 expressing CHO cells. Analysis of T helper-cell subsets revealed that memory T cells bound several fold stronger to ICAM-1 expressing transfectants compared to the CD4⁺ 45RA⁺ naive T cells, whereas adhesion to B7, LFA-3- and B7/LFA-3-expressing CHO cells was similar in both T-cell subsets. The kinetics of adhesion of naive and memory CD4⁺ T cells to ICAM-1 was rapid and similar in both subsets. The NKI-L16 MoAb multiplied several times ICAM-1-dependent adhesion in naive compared to memory cells, which enabled the naive cells to reach a similar adhesion level as memory cells. The results suggest that resting naive CD4⁺ T cells utilize preferentially the CD2/LFA-3 or CD28/B7 adhesion pathways upon adhesion to APCs, while memory CD4⁺ T cells utilize the CD2/LFA-3, CD28/B7 and LFA-l/ICAM-1 adhesion pathways. The NK.I-L16 MoAb-induced upregulation of adhesion involves an increased affinity of LFA-1 for its ligand and not a change in the number of LFA-1 molecules. This is compatible with a view that naive cells express a large number of inactive LFA-1 molecules, whereas memory cells express preferentially activated LFA-1 molecules. The inherent low number of active LFA-I molecules on naive CD4⁺ T cells may be important in keeping these cells in a resting state.     

Activation of Resting, Pure CD4+, and CD8+ Cells via CD3

We studied the requirements for secondary activation signals in pure CD4+ and CD8+ T cells after stimulation with anti-CD3 antibodies. Stimulation of CD4+ or CD8+ cells with anti-CD3 monoclonal antibodies (MoAb) bound to polystyrene monosized particles never resulted in a proliferative response. However, DNA synthesis was observed when recombinant interleukin 2 (IL-2) or other secondary signals, such as those provided by phorbol myristate acetate (PMA) or autologous accessory cells (AC), were also added. These secondary signals were not in themselves capable of inducing DNA synthesis in the absence of particle-bound anti-CD3. We also found that the signals provided by AC may be dependent on the activation state of these cells. Thus, the effects of accessory cells were enhanced by a factor present in fetal calf serum (FCS), most likely endotoxin or lipopolysaccharide (LPS), which alone, however, were not able to activate T cells, even in the presence of particle-bound anti-CD3. Recombinant IL-1 over a broad dose range was unable to replace PMA or activated AC after stimulation with particle-bound anti-CD3. Purified CD4+ and CD8+ T cells behaved identically in all the experiments, indicating that the basic mechanisms for activation in the two T-cell subsets are identical.     

Acquisition of Interleukin-5 Secretion by Human Naive T-Helper Cells is Regulated by Distinct Signals from both the T-Cell Receptor/CD3 Complex and CD2

We developed a human naive T-helper (Th) cell differentiation model with anti-CD3 monoclonal antibody (MoAb), using a B-cell line as source of costimulation. In this system, we examined the contribution of the T-cell receptor (TCR)/CD3-derived signals and that of lymphocyte function-associated antigen-1 (LFA-1) and CD2 in regulating Th-cell subset differentiation. We found that lowering the level of anti-CD3 MoAb decreased tumour necrosis factor-α (TNF-α) production, while increasing secretion of the Th2 cytokines, interleukin-5 (IL-5) and interleukin-13 (IL-13). Secretion of interferon-γ (IFN-γ) was not influenced by the strength of the anti-CD3 signal. Under conditions where Th0 cells are generated, co-culture with anti-CD2 F(ab')₂ MoAb led to the generation of Th cells that secreted 30–35% less IL-5, while not affecting secretion of IFN-γ or granulocyte–macrophage colony-stimulating factor (GM-CSF). By contrast, anti-CD18 MoAb F(ab')₂ inhibited IFN-γ and GM-CSF levels only in the primary stimulation, but did not affect cytokine levels after restimulation. Neither anti-CD2 nor anti-CD18 F(ab')₂ MoAbs could alter cytokine secretion profiles of peripheral blood-derived memory/effector Th cells. Our results indicate that acquisition of IL-5 secretion capability by Th cells is regulated mainly by signals transduced by the TCR/CD3 complex and by the presence of interleukin-4 (IL-4), while the CD2/LFA-3 pathway plays an additional, but minor, role. These regulatory CD2-derived signals, however, are distinct from those generated by the TCR/CD3 complex.     

High IL-10 production by aged AIDS patients is related to high frequency of Tr-1 phenotype and low in vitro viral replication

This work aims to elucidate the effects of age and HIV-1 infection on the frequency and function of T cell subsets in response to HIV-specific and non-specific stimuli. As compared with the younger AIDS group, the frequencies of naive and central memory T cells were significantly lower in aged AIDS patients. Although there was also a dramatic loss of classical CD4(+)FoxP3(+)CD25(+)Treg cells in this patient group, high frequencies of IL-10-producing CD4(+)FoxP3(-) T cells were observed. In our system, the increased production of IL-10 in aged AIDS patients was mainly derived from Env-specific CD4(+)FoxP3(-)CD152(+) T cells. Interestingly, while the blockade of IL-10 activity by monoclonal antibody clearly enhanced the release of IL-6 and IL-1β by Env-stimulated PBMC cultures from aged AIDS patients, this monoclonal antibody enhanced in vitro HIV-1-replication. In conclusion, HIV infection and aging undoubtedly contribute synergistically to a complex immune dysfunction in T cell compartment of HAART-treated older HIV-infected individuals.     

Immune accessory functions of human endothelial cells are modulated by overexpression of B7-H1 (PDL1)

B7-H1 (PDL1) is a B7-related protein that inhibits T-cell responses. Human endothelial cells (EC), which can support polyclonal stimulation (by anti-CD3 or Phytohemagglutinin (PHA)) or direct alloantigen stimulation of T cells, basally express B7-H1 and increase expression in response to IFN-gamma or coculture with allogeneic T cells. Previous studies have suggested that endogenous B7-H1 on EC reduces T-cell responses. We engineered overexpression of B7-H1 in EC (B7H1-EC) to evaluate whether this manipulation could reduce T-cell responses even further. Compared with green fluorescent protein-transduced EC (GFP-EC), B7H1-EC support less anti-CD3 or PHA-induced proliferation of CD4+ memory T cells; naive CD4+ T-cell or CD8+ T-cell responses were less inhibited. The effect of transduced B7H1-EC was more apparent when the EC were fixed prior to coculture, a manipulation that reduces the strength of costimulation and prevents upregulation of the endogenous B7-H1 molecule. T-cell activation markers, including CD25, CD62L, CD152 (CTLA-4), and CD154 (CD40L), were not altered by EC overexpression of B7-H1, whereas there was a reduction in CD69. B7-H1 reduced secretion of IL-2 and IL-10 by memory T cells. B7H1-EC were less able to stimulate allogeneic proliferation of CD4+ memory T cells than control EC. These data suggest that B7-H1 overexpression may be a useful approach for reducing allogeneic CD4+ memory T-cell responses to EC.     

Stimulated proliferative responses in vertically HIV-infected children on HAART correlate with clinical and immunological markers

The objective of the study was to investigate the relationship between various CD4+ T cell subsets and the ability of peripheral blood mononuclear cells (PBMC) to proliferate to several stimuli in vertically human immunodeficiency virus type 1 (HIV-1)-infected children. We studied 29 HIV-1-infected children on highly active antiretroviral therapy (HAART) (median duration: 12.3 months). T cell subsets were determined by flow cytometry. Plasma viral load (VL) was quantified using a standardized molecular method. Proliferative responses were evaluated by [3H]-thymidine incorporation. Decreased proliferative responses of PBMC to pokeweed mitogen (PWM) were found for HIV-1-infected children in Centers for Disease Control (CDC) clinical categories B and C when compared to the control group (P < 0.05). Similarly, children with < or = 15% CD4+ T cells showed a decrease in proliferative responses to PWM (P < 0.01), anti-CD3 + anti-CD28 (P < 0.01) and phytohaemagglutinin (PHA) (P < 0.05) with respect to the control group and to children with CD4+ T cells > or = 25%. Proliferative responses to PWM, anti-CD3+, anti-CD28 and PHA had a statistically significant positive correlation with CD3+/mm3, CD4+/mm3, % CD4 T cells, CD4/CD8 ratio and the percentage of naive T cell subsets (CD4+CD45RO-HLA-DR-, CD4+ CD45RA+ CD62L+, CD4+ CD45RA+), CD4+ CD62L+ and CD4+ T cells co-expressing CD38+ (CD4+ HLA-DR-CD38+, CD4+ CD38+). Moreover, we found a negative correlation between PBMC proliferative responses and % CD8 T cells, memory, memory-activated and activated CD4+ T cell subsets. Lower proliferative responses to PWM (P < 0.01) and PHA (P < 0.01) were associated with higher VL. Our data show that higher proliferative responses to PWM, anti-CD3 + anti-CD28 and PHA are associated with both non-activated and naive CD4+ T cell subsets in HIV-1-infected children on HAART.     

Defective functional response to membrane stimuli in lymphocytes from patients with benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is a local disturbance in the prostate that may involve an inflammatory infiltrate predominantly composed of activated lymphocytes and macrophages. The activation and proliferative response of T lymphocytes to different mitogenic signals has been analysed in peripheral blood mononuclear cells (PBMC) from 45 patients with BPH and 55 healthy controls. The PBMC obtained from the patients showed a significant specific impairment in proliferation, CD25 expression and IL-2 production in response to stimulation with lectins (phytohaemagglutinin (PHA), concanavalin A (Con A)), that was not corrected by the addition of IL-2 or of phorbol esters (phorbol myristate acetate (PMA)). Also, the CD28 response was defective in patient PBMC. Activation with anti-CD3 or anti-CD2 MoAbs was normal, but the addition of PMA to these stimuli provoked a significant defective response. Only the use of transmembrane stimuli (PMA and ionomycin) elicited responses similar to those found in the control group. The results indicate that peripheral T lymphocytes from BPH patients show a functional impairment that is mainly explained by an alteration of membrane signals (PHA, CD28) and is distal to protein kinase C (PKC) activation.     

Interferon-gamma secretion of peripheral blood CD8+ T lymphocytes in patients with bronchial asthma: in vitro stimulus determines cytokine production.

It has been postulated that T lymphocytes orchestrate the chronic inflammation in bronchial asthma. In animal models, infiltration of CD8+ T lymphocytes into the bronchial mucosa prevented bronchial hyperresponsiveness and decreased early and late phase reaction. IFN-gamma antagonizes IL-4-dependent IgE production as well as IL-5-induced proliferation and activation of eosinophils. We therefore investigated the secretion of IFN-gamma of isolated CD8+ T lymphocytes from peripheral blood of patients with allergic asthma (n = 6) and from healthy controls (n = 7) in vitro. In this setting we compared the effect of stimulation with anti-CD3 antibodies with that of phorbol myristate acetate (PMA) and calcium-ionophore. As expected, CD8+ T lymphocytes from peripheral blood of healthy volunteers produced significantly more IFN-gamma in the presence of PMA and calcium-ionophore than after stimulation with anti-CD3 antibodies. However, in subjects with allergic asthma, IFN-gamma secretion of CD8+ T cells was significantly higher when incubated with anti-CD3 antibodies than after activation with PMA and calcium-ionophore. While IFN-gamma secretion of CD8+ T lymphocytes of patients with allergic asthma was lower than that of healthy controls in the presence of PMA/calcium-ionophore, it was significantly elevated when compared with normal controls after stimulation with anti-CD3 antibodies. Thus, potent activators of cytokine secretion, such as PMA and calcium-ionophore, induce a cytokine profile different from that induced by weaker stimulants, such as anti-CD3 antibodies. These findings have implications for further studies investigating cytokine production of inflammatory cells in vitro.     

Human naive CD4 T cells produce interleukin-4 at priming and acquire a Th2 phenotype upon repetitive stimulations in neutral conditions

The maturation of naive CD4 T cells into interleukin (IL)-4-producing effectors was shown to require the presence of IL-4 at priming, the cellular origin of which remains unclear. We demonstrate here that naive T cells themselves release IL-4 at very low levels that are nevertheless sufficient to promote their development into Th2-like cells. This conclusion is based on three observations: (1) highly purified human naive CD4T cells, of neonatal or adult origin, develop into Th2 effectors upon repetitive cycles of stimulation with anti-CD3 monoclonal antibody (mAb) cross-linked to CD32-B7 transfected L fibroblasts followed by IL-2 expansion; (2) IL-4 protein is readily detectable in the concentrated supernatant fluids of priming cultures performed in the presence of anti-IL-4 receptor mAb; and (3) addition of anti-IL-4 or anti-IL-4 receptor mAb at priming markedly inhibits the acquisition of IL-4- and IL-5-producing capacity while enhancing that of interferon-γ.     

Immobilized anti-CD3 mAb induces anergy in murine naive and memory CD4+ T cells in vitro

The induction of non-responsiveness in resting murine CD4+ T cells was investigated using immobilized anti-CD3 mAb. Incubation of freshly isolated CD4+ T cells with immobilized anti-CD3 mAb led to apoptosis in 40-60% cells. The surviving cells were profoundly non-responsive to subsequent mitogenic stimulation. The non-responsive state was characterized by a lack of IL-2 production and hyper-responsiveness to added IL-2, but was not explained by further activation-induced cell death. The induction of non-responsiveness was not due to modulation of the TCR-CD3 complex, and required partial activation of the T cells in that it was accompanied by an increase in cell size and was inhibited by addition of cyclosporin A. Finally, analysis of anti-CD3-mediated responses in naive and memory CD4+ T cells, separated on the basis of CD44 expression, showed that both naive and memory T cells have similar sensitivity to immobilized anti-CD3 mAb-induced activation, apoptosis and anergy. These results demonstrate that TCR-CD3 engagement on freshly isolated resting CD4+ naive and memory T cells, In the absence of co-stimulation, as achieved by plastic-immobilized anti-CD3 mAb, induces both anergy and cell death.      

Naive T cells from cord blood have the capacity to make Types 1 and 2 cytokines

We wanted to determine whether naive T cells could make the Types 1, 2 and 0 defining cytokines Interleukin (IL)-4 and Interferon (IFN)gamma. We show that stimulation of naive T cells (CD3+ CD45RA+) derived from cord blood by phorbol ester (phorbol-12-myristate-13-acetate: PMA) plus lonomycin induced detection of Types 1, 2 and 0 cells. Conversely, when we stimulated the naive T cells through the T cell receptor (with anti-CD3 monoclonal antibody alone) there was no detection of IFNgamma or IL-4 producing cells. Stimulation with PMA and CD3 induced detection of only Type 2 cells. This unexpected finding shows that there is a high frequency of Type 2 cells within the naive T cell population, contrary to previously published reports. The highest percentage of Type 2 naive cells (10.5%) was obtained with 50 ng/ml PMA plus 50 microg/ml anti-CD3. Thus, we have shown that naive T cells derived from cord blood have the capacity to make both Types 1 and 2 cytokines and the frequency of cells producing these cytokines can be greater than 20%, depending on the stimulus used.     

两种多克隆刺激条件下人诱导性Treg表型的多样性变化

目的:研究人诱导性调节性T细胞(iTreg)细胞表型的多样性变化,并比较PMA/Ionomycin和PHA两种多克隆刺激对人iTreg的诱导的异同。方法:用Ficoll密度梯度离心分离出人PBMC,空白对照组直接检测,其余则在细胞培养液(非刺激对照组)、PMA/Ionomycin溶液(PMA/Ionomycin刺激组)或PHA溶液(PHA刺激组)中培养16小时,以流式细胞仪检测CD4+CD25+FoxP3+CD127-、CD4+CD25+FoxP3+IL-2-、CD4+CD25+FoxP3+IL-10+、CD4+CD25+FoxP3+TGF-β+和CD4+CD25+FoxP3+IFN-γ+的表达。结果:空白对照组显示,约4%的CD4+细胞表达CD4+CD25+FoxP3+CD127-,即nTreg。PBMC在细胞培养液培养16个小时,iTreg的表达无明显变化,但经多克隆刺激后,各不同细胞表型的iTreg的表达明显上升(均P<0.01),表明多克隆刺激可以明显诱导人iTreg的产生。PHA对IL-2-和TGF-β+iTreg的诱导比PMA/Ionomycin强(P<0.01),但仅PMA/Ionomycin可以诱导产生CD4+CD25+FoxP3+IFN-γ+iTreg,而PHA不能诱导。刺激后产生的CD4+FoxP3+IFN-γ+PBL表达与CD25水平呈逆相关。结论:多克隆刺激可以诱导产生人iTreg,PMA/Ionomycin和PHA对人iTreg诱导的机制和程度不一样。多克隆刺激后产生的不同细胞表型反映了人iTreg的多样性变化。     

Reduced naive and increased activated CD4 and CD8 cells in healthy adult Ethiopians compared with their Dutch counterparts

To assess possible differences in immune status, proportions and absolute numbers of subsets of CD4+ and CD8+ T cells were compared between HIV- healthy Ethiopians (n = 52) and HIV- Dutch (n = 60). Both proportions and absolute numbers of naive CD4+ and CD8+ T cells were found to be significantly reduced in HIV Ethiopians compared with HIV- Dutch subjects. Also, both proportions and absolute numbers of the effector CD8+ T cell population as well as the CD4+CD45RA-CD27- and CD8+CD45RA-CD27- T cell populations were increased in Ethiopians. Finally, both proportions and absolute numbers of CD4+ and CD8+ T cells expressing CD28 were significantly reduced in Ethiopians versus Dutch. In addition, the possible association between the described subsets and HIV status was studied by comparing the above 52 HIV- individuals with 32 HIV+ Ethiopians with CD4 counts > 200/microliter and/or no AIDS-defining conditions and 39 HIV+ Ethiopians with CD4 counts < 200/microliter or with AIDS-defining conditions. There was a gradual increase of activated CD4+ and CD8+ T cells, a decrease of CD8+ T cells expressing CD28 and a decrease of effector CD8+ T cells when moving from HIV- to AIDS. Furthermore, a decrease of naive CD8+ T cells and an increase of memory CD8+ T cells in AIDS patients were observed. These results suggest a generally and persistently activated immune system in HIV- Ethiopians. The potential consequences of this are discussed, in relation to HIV infection.