Immunoregulatory T cell subsets and T cell activation in rheumatoid arthritis

Conclusion Activation of T cell may be accomplished following the interaction of the TCR-CD3 complex with antigen and MHC products. In vitro this may be replaced by antibodies to the TcR or CD3 complex which mimic ligand binding. So called alternative pathways may also trigger activation. Activational state may be measured by lymphokine production, proliferative capacity or by expression of activation antigens. By these criteria a proportion of T cells isolated from rheumatoid joints appear to have undergone an in vivo activation. Phenotypic analysis of the synovial T cells has also established that there is an unusual distribution of T and T cells and T cell subsets in many rheumatoid patients. As T cells play a central role in immunoregulation, further exploitation of these observations using T cell clones and molecular techniques will extend our understanding of the disease process. In particular, further knowledge is required on the possible role of T cells in RA, the clonality of the T cells, the possible use of alternative activation pathways, and ultimately, the specificity of these T cells.     

Colony formation by subpopulations of T lymphocytes. IV. Inhibitory effect of hydrocortisone on human and murine T cell subsets.

The sensitivity of human T lymphocyte colony formation to hydrocortisone (HCS) was studied in the presence and absence of an exogenous source of interleukin-2(IL-2). In the presence of IL-2, T colony formation by T inducer/helper (Th) cells was found to be 100-fold more resistant to the inhibitory effect of HCS in vitro than colony formation by T suppressor/cytotoxic (Tsc) cells, the IC50 values for HCS being 10(-4)M and 10(-6)M, respectively. In the absence of IL-2,Tsc cells do not form colonies and T cell colony formation by Th cells is inhibited 50% by less than 5 x 10(-8)M HCS. T lymphocyte colony formation by murine cortical thymocytes in vitro was inhibited by physiological concentrations of HCS in vitro, the IC50 value being 2 x 10(-8)M HCS. T cell colony formation by medullary thymocytes and peripheral lymphocytes was found to be 100-fold more resistant to HCS than control cells, the IC50 value being 2 x 10(-6)M HCS.     

A selective effect upon IgG synthesis by T gamma lymphocytes and their products in man

Depletion of T lymphocytes possessing receptors for IgG (T gamma cells) from peripheral blood lymphocytes (PBL) results in enhanced pokeweed mitogen (PWM)-induced IgG synthesis and secretion as compared to IgM. Concanavalin A (Con A) stimulation of T gamma cells causes release of soluble mediators able to suppress immunoglobulin synthesis by PWM-activated PBL. Such factors cause concentration-dependent selective suppression of IgG synthesis. The mediators act upon T gamma cell-depleted lymphocyte populations, also preferentially suppressing the IgG PFC response while leaving the IgM response relatively intact. Thus T gamma cells and their products selectively affect IgG synthesis in vitro.     

In vitro synthesis of IgG by peripheral blood lymphocytes in chronic liver disease.

In vitro IgG synthesis by peripheral blood mononuclear cells (PBM) from patients with chronic liver disease (CLD) was studied. In addition, the effect of pokeweed mitogen (PWM), polyadenylic-polyuridylic acid complexes (poly A:U) and thymosin fraction 5 on IgG synthesis was determined. Unstimulated cultures of PBM from patients with chronic active hepatitis (CAH) and alcoholic cirrhosis (AC) synthesized significantly higher quantities of IgG than the controls. Moreover, there was a direct correlation between serum IgG concentrations and the quantity of newly synthesized IgG in these unstimulated cultures. PWM, poly A:U and thymosin each stimulated increased IgG synthesis in the controls. While neither poly A:U nor thymosin enhanced IgG synthesis in patients with CLD, PWM increased IgG synthesis in CAH but not AC. These results indicate that spontaneous in vitro B cell synthesis of IgG is enhanced in CLD and may reflect antigenic stimulation in vivo.     

1,25二羟维生素D3对人淋巴细胞免疫功能的调节作用

通过淋巴细胞增殖试验、混合淋巴细胞反应及分析淋巴细胞表面IL-2R 和TfR 表达等研究了1.25-(OH)_2D_3对人淋巴细胞的免疫调节作用。结果表明,1,25-(OH)_2D_3对PHA 诱导的淋巴细胞增殖有抑制作用,IC_(50)为19.1nmol/L 外源性IL-2可部分逆转这种作用;低浓度的1,25-(OH)_2D_3能显著增强MLR 诱导的细胞增殖;在由PHA 和MLR 诱导的淋巴细胞表面IL-2R 和TfR 表达中,对TfR 的表达呈抑制作用,对IL-2R 的表达无影响。     

人脐血间充质干细胞对T淋巴细胞旁分泌的免疫调节作用

背景：相关研究表明脐血间充质干细胞具有一定的免疫调节作用,但具体机制不详。 目的：观察脐血源间充质干细胞通过旁分泌机制对T淋巴细胞增殖的影响。 方法：分离正常分娩产妇脐血间充质干细胞和健康志愿者外周血T淋巴细胞,按不同比例建立脐血间充质干细胞与T淋巴细胞非接触共培养体系,以单独培养T淋巴细胞作为对照组。 结果与结论：脐血间充质干细胞形态学呈现成纤维梭型细胞样,呈旋涡状团集生长。流式细胞仪检测脐血间充质干细胞表面标记物：CD29(+),CD44(+),CD34(-),CD45(-),HLA-DR(-);与对照组相比,共培养组可明显抑制植物血凝素刺激T淋巴细胞的增殖作用(P < 0.05),且呈剂量依赖性;ElISA法检测共培养组分泌的白细胞介素10水平较对照组明显升高(P < 0.05);中和试验后脐血间充质干细胞对T淋巴细胞增殖的抑制作用明显减弱。结果说明脐血间充质干细胞可明显抑制异体外周血T淋巴细胞的增殖,可能是通过旁分泌白细胞介素10达到负向免疫调节作用。     

The distribution and function of human memory T cell subsets in lung cancer

The distribution and function of T lymphocytes in human lung cancer remain limited. In this study, we investigated the properties of human T cell subsets in the blood of non-small cell lung cancer (NSCLC) patients. We found a relatively normal level of CD4+ subsets in the blood of NSCLC patients, but CD8+ effector T cells increased and CD8+ effector memory cells declined compared to the healthy donors. To further analyze their properties, we stimulated the peripheral blood mononuclear cells (PBMCs) of NSCLC patients by mitogens to examine cytokine production. Our data suggest that both CD4+ and CD8+ naïve cells in NSCLC patients significantly reduced IFN-γ and TNF-α production. Additionally, fewer CD8+ effector cells produced IFN-γ and TNF-α in NSCLC patients than in healthy subjects. Moreover, similar results were observed for CD4+ or CD8+ memory cells in NSCLC patients for the production of IFN-γ, TNF-α, and IL-17. Therefore, our results strongly suggest that the function of CD4+ and CD8+ T lymphocytes in NSCLC patients is compromised or dysregulated. The development of vaccines and antitumor immunotherapy may be essential for the treatment of lung cancer patients.     

The inductive effect of interleukin-4 on IgG4 and IgE synthesis in human peripheral blood lymphocytes

Using murine monoclonal antibodies against human IgG subclasses, specific and sensitive ELISAs assay to quantify the four human IgG subclasses in cell culture supernatants were established. The effect of human recombinant interleukin-4 (IL-4) on the regulation of IgG subclasses by normal peripheral blood lymphocytes was investigated. In addition to the enhancement of IgE synthesis, IL-4 preferentially induced IgG4 synthesis in vitro, whereas IL-4 had no effect on IgG1, IgG2, and IgG3 synthesis. IL-4-induced IgG4 production was blocked in a dose-dependent manner by recombinant interferon-gamma and anti-human IL-4 monoclonal antibody. Collectively, this data indicates that IL-4 plays an important regulatory role in both IgG subclass and IgE synthesis.     

Regulation of B cell immunoglobulin secretion by functional subsets of T lymphocytes in man

Two distinct immunoregulatory T cell subsets, termed T4⁺ and T5⁺, have been defined in man by monoclonal antibodies. Prior studies have shown that the T4⁺ T cell population provided help for B cell immunoglobulin (Ig) production and was required for generation of T5⁺ cytotoxic effector cells. In the present study, the regulatory effects of the T5⁺ T cell subset on B cell Ig secretion were determined in a pokeweed mitogen-driven system. It was found that the T5⁺ subset, in contrast to the T4⁺ subset, was incapable of providing help to B cells and, more importantly, could suppress Ig secretion by B cells in the presence of T4⁺ inducer T cells. Given earlier studies demonstrating that the T5⁺ T cell subset suppressed T cell responses as well, this population appears to represent the major suppressor subset in man for T-T and T-B interactions.     

Induction of T cell growth factor synthesis in human peripheral blood lymphocytes by staphylococcal protein A

Staphylococcal Protein A (SpA) induces T cell growth factor (TCGF) production in cultures of human peripheral blood mononuclear cells (PBMC) with titers equivalent to those induced by PHA. The optimal time and cell concentration for TCGF production were found to be the same for SpA and PHA. TCGF induction by SpA was blocked by addition of human AB-serum or human IgG, as was the mitogenic effect of SpA. An easy and inexpensive procedure is described for the quantitative removal of SpA from TCGF without loss of TCGF activity.     

Age-related changes of T cell subsets in intestinal intraepithelial lymphocytes of mice

Age-related changes in T cell subsets were examined in intestinal intraepithelial lymphocytes (i-IEL), which contain unique T cells differentiating extrathymically. In 2-month-old mice bred under conventional condition, i-IEL consisted of a large number of CD4^?CD8α/α⁺ cells bearing either T cell receptor (TcR)α/β or TcRγ/δ and only a few CD4⁺CD8α^? cells. In aged mice (6 months old and 24 months old), unique CD4⁺CD8α/α⁺ i-IEL bearing TcRα/β increased in number and conversely the proportion of TcRγ/δ⁺ i-IEL was decreased. Such an increase in number of CD4⁺CD8α/α⁺ cells was detected in i-IEL from aged (14-months old) nude mice, but not in aged (14 months old) germ-free mice, suggesting that a significant fraction of TcRα/β T cells such as CD4⁺CD8α⁺ i-IEL can develop along an extrathymic pathway under the influence of intestinal microflora with age.     

Functional properties of subsets of T lymphocytes defined by specific antigens.

Heteroantisera raised to the acute lymphocytic T (ALL) cell line HSB2 and to Sézary cells react with distinct subpopulations of T lymphocytes. Each antiserum reacts with a different T cell antigen and defines a distinct subpopulation that represents approximately 50% of peripheral blood T lymphocytes. The anti-HSB2-positive subpopulation contained suppressor cells for pokeweed mitogen-dependent immunoglobin (Ig) synthesis whereas the anti-Sézary cell serum-positive population included helper cells for Ig synthesis and mixed lymphocyte responder cells.     

HLA-DR phenotypes and blood levels of T cell subsets

Blood mononuclear cell and T cell subsets values were analyzed in 53 Sicilian individuals according to HLA-DR phenotypes. The results demonstrate that DR1-positive subjects show a significant increase of blood T cell subsets whereas DR3-positive subjects show a non-significant decrease of these values. These results suggest that gene(s) associated with HLA-DR could be one of the factors which affect blood levels of T cell subsets.     

Immunoregulatory effects of interferon-alpha. I. Interferon-alpha inhibits in vitro antibody synthesis by normal human lymphocytes.

The effects of human interferon-alpha (IFN-alpha) on in vitro synthesis of specific anti-influenza virus antibody were measured in cultures of peripheral blood lymphocytes from normal donors. IFN-alpha suppressed antibody synthesis in a time and dose related manner. This suppression was also produced by monoclonal antibody purified IFN-alpha and was blocked by anti-IFN-alpha antibody. However antibody induced by a combination of antigen and 'B cell helper supernatant' was not suppressed indicating that IFN-alpha inhibits the initial events in antibody synthesis but does not affect cells committed to antibody production.     

Variation in peripheral blood T cell subsets in serial assays

No significant differences were found in the T cell subsets of fresh and frozen peripheral blood mononuclear cells (PBM) from six healthy donors analysed with the Ortho series of monoclonal antibodies and a fluorescence-activated cell sorter. Analysis of replicates of cryopreserved PBM showed that considerably higher variation in T cell subsets occurred when samples were assayed in serial assays than when the samples were analysed together under the same conditions. These results indicate that errors introduced into a longitudinal study by serial analysis of samples may be reduced if samples are cryopreserved and subsequently thawed and analysed together at the end of the study.     

The expanding universe of regulatory T cell subsets in cancer

Evidence has indicated that failed antitumor immunity is dominated by immunosuppressive mechanisms within the tumor microenvironment. In this issue of Immunity, Peng et al. (2007) add to this list by describing tumor-infiltrating gammadelta T cells that have regulatory function.     

Immunoregulatory cell subsets in Goodpasture's syndrome: Evidence for selective T suppressor-cell depletion during active autoimmune disease

In a patient with documented untreated Goodpasture's syndrome, serial determination of T-cell subsets using monoclonal antibodies and flow cytometry revealed a persistent but variable deficiency of T-suppressor cells during the period of active disease. As the percentage of OKT8+ cells (suppressor/cytotoxic T cells) returned to normal levels, anti-basement membrane autoantibody production decreased and finally disappeared. Possible pathogenetic implications of immunoregulatory cell imbalance specifically in reference to Goodpasture's syndrome are discussed.     

Immune compartmentalization of T cell subsets in chemically-induced breast cancer

In cancer, the phenotype and/or the function of T cells may differ according to their distribution through immune-associated tissues, namely immune compartments. Here, in N-methyl-N-nitrosourea (MNU)-induced mammary carcinomas of rat as a relevant model for human breast tumors, the impact of tumor burden on the T cell subsets populating the tumor microenvironment, the tumor-adjacent and -opposite mammary lymph nodes, and the spleen was assessed. In the tumors, ratio of CD8(+) cytotoxic and CD4(+) helper T cells were not significantly different than other immune compartments. On the other hand, most of these cells were further identified with CD4(+) CD25(hi) or CD4(+) Foxp3(+) , CD8(+) Foxp3(+) regulatory phenotype. The selective presence of Tregs in the mammary tumors but not in neighboring-mammary tissue was also confirmed by the expression of Treg-associated genes. The percentage of CD161(+) NKT cells was also significantly increased especially in the tumors and mammary lymph nodes. In the lymph nodes of tumor-bearing animals, in contrast to the spleen, total amount of CD8(+) cells and CD4(+) cells were increased but both of these compartments harbored high numbers of CD4(+) CD25(hi) Treg cells. TGF-β was determined as the major suppressive cytokine secreted by the immune cells of tumor-bearing animals, in addition, proliferation capacity of the T cells was diminished. Hence, the differential distribution of T cell subsets through the spleen, the mammary lymph nodes and the tumor mass in MNU-induced mammary tumor-bearing animals may contribute to a tumor-associated immunosuppression.     

Immunoregulatory effects of morphine on human lymphocytes.

It is now well established that parenteral drug abuse is a significant risk factor for contracting human immunodeficiency virus type 1 (HIV-1) infection and subsequently developing AIDS. Earlier studies have shown that morphine can modulate various immune responses and therefore support the premise that morphine is a cofactor in susceptibility to and progression of HIV infection. Dysregulation of interferon (IFN) production, nonspecific apoptosis of T cells, and the immune response to soluble HIV gene products have been associated with potential mechanisms of pathogenesis in HIV disease. The present study was undertaken to examine the immunomodulatory role of morphine on HIV protein-induced lymphocyte proliferative responses, Sendai and Newcastle disease virus-induced alpha IFN (IFN-alpha) and IFN-beta production by lymphocytes and fibroblast cells, respectively, and induction of apoptosis of normal lymphocytes in vitro. Our results demonstrate that HIV protein-induced human lymphocyte proliferative responses were significantly inhibited by morphine in a dose-dependent manner. Furthermore, morphine significantly inhibited both IFN-alpha and IFN-beta production by normal lymphocytes and fibroblasts but induced apoptosis of normal lymphocytes. Inhibition of IFN-alpha production by morphine could be reversed by the opiate receptor antagonist naloxone. This suggests that the immunomodulatory effects of morphine are mediated through the opioid receptor. These studies support a role of morphine as a cofactor in the pathogenesis of HIV infection and describe some of the possible pathologic mechanisms which underlie the immunoregulatory effects of morphine.     

Lymphocyte subsets and mitogen stimulation of blood lymphocytes in preeclampsia.

PROBLEM: The question of whether there are differences in systemic immune reactivity in severe preeclampsia compared with normal pregnancy was addressed. METHOD OF STUDY: During the third trimester, blood samples were taken from 12 pregnant women with severe preeclampsia. Five of the preeclamptic pregnancies were analyzed separately because they were treated with dexamethasone before the blood samples were taken. The seven dexamethasone-treated preeclamptic pregnant women were analyzed and compared with six uncomplicated pregnancies. A control group consisted of 15 nonpregnant females. Lymphocyte subsets were identified by flow cytometry. The function of peripheral blood mononuclear cells (PBMCs) was studied as proliferative responses to mitogens alone and in combination with immunomodulating drugs. RESULTS: An increased number of B lymphocytes (CD19+) (P < 0.05) and natural killer (NK) cells (P < 0.05) was noticed in severe preeclampsia compared with normal pregnancy. The proliferative response of PBMCs in phytohemagglutinin (PHA)-stimulated cultures in autologous serum from patients with severe preeclampsia was reduced (P < 0.05) compared with normal pregnancy. The addition of indomethacin and cimetidine significantly stimulated (P < 0.05) the proliferative responses. The enhancing effect of cimetidine was not found in dexamethasone-treated preeclamptic patients. CONCLUSIONS: The presence of systemic immunosuppression in severe preeclampsia is demonstrated as a reduced proliferative response of PBMCs to PHA, which could be partly restituted by indomethacin or cimetidine, indicating immunosuppressor activity that is mediated by prostaglandin and histamine. Increased levels of B lymphocytes and NK cells were also noticed.