CD8+ T cells control Th2-driven pathology during pulmonary respiratory syncytial virus infection

BALB/c mice vaccinated with vaccinia virus expressing the major surface glycoprotein G of respiratory syncytial virus (RSV) develop lung eosinophilia during RSV challenge. The G protein is remarkable in that it induces CD4⁺, but no CD8⁺ T cells in this mouse strain. Studies using passive T cell transfers show that co-injection of CD8⁺ T cells greatly reduces the Th2-driven lung eosinophilia caused by G-specific CD4⁺ T cells. By contrast, vaccination with the fusion protein (F) induces both CD8⁺ and CD4⁺ T cells, but not lung eosinophilia during RSV infection. These observations suggest that CD8⁺ T cells play a crucial role in preventing Th2-driven pathology. We therefore depleted mice with anti-CD8 antibodies in vivo. This treatment allowed lung eosinophilia to develop in F-primed mice. Depletion of interferon (IFN)-γ had a similar effect, suggesting that secretion of this cytokine is the mechanism by which CD8⁺ T cells exert their effect. To test whether similar effects occurred in other strains of mice, RSV-infected C57BL/6 mice (which do not develop eosinophilia after sensitization to G) were treated with anti-IFN-γ. Again, these mice developed eosinophilia. In this strain, genetic deletion of CD8-α, β2-microglobulin or genes coding for the transporter associated with antigen presentation (which in each case eliminates CD8⁺ T cells) caused lung eosinophilia during RSV infection. These studies show the critical roles that CD8⁺ T cells and IFN-γ production play in regulating Th2-driven eosinophilia and provide a unifying explanation for previous studies of lung eosinophilia. We propose that vaccines designed to enhance CD8⁺ T cell recognition might avoid disease caused by CD4⁺ Th2 cells.     

Relative importance of CD4+ and CD8+ T cells in the resolution of Chlamydophila abortus primary infection in mice

The role of the specific cellular immune response is well established in Chlamydiaceae infections, but the importance of each T-cell subset seems to be species-dependent. This study was designed to clarify the role of T-cell subsets in the response to Chlamydophila abortus primary infection. C57BL/6 mice were depleted of CD4+ or CD8+, or both, by monoclonal antibody injections and subsequently infected with C. abortus. Mice were killed at intervals and samples were collected for bacteriological and histopathological analysis. Also carried out were spleen cell culture, cytokine quantification, immunolabelling for C. abortus antigen, and a TUNEL assay for apoptosis. CD8+ T cell-depleted mice all died within 12 days of C. abortus infection, while no mortality was observed in the other groups; surprisingly, CD4+ T cell-depleted mice showed lower morbidity (expressed as weight loss) than did a non-depleted (control) group. CD8+ T cell-depleted mice also differed from the other groups in showing a significantly higher chlamydial burden in the liver. CD8+ T cell-depleted mice also had a higher number of apoptotic cells in hepatic inflammatory foci and showed exacerbated IFN-gamma production by spleen cells after specific stimulation. Simultaneous depletion of both T-cell subpopulations led to a chronic infection, but not to early mortality. It is concluded that CD8+ T cells may play a role in the regulatory control of the CD4+ T-cell response and may have a direct cytotoxic or IFN-gamma-mediated effect on infected cells.     

Marked anti-tumor effects of CD8+CD62L+ T cells from melanoma-bearing mice

CD8⁺CD62L⁺ T cells have been shown to play pivotal roles in anti-viral immunity, chronic myeloid leukemia and renal cell carcinoma. Recently, CD8⁺CD62L⁺ T cells from naïve mice (nCD8⁺CD62L⁺ T cells) have shown superior anti-tumor properties in melanoma-bearing mice. Considering that antigen-specific memory T cells have shown to possess more potent immunity than non-specific memory T cells, we hypothesized that CD8⁺CD62L⁺ T cells from tumor-bearing individuals (mCD8⁺CD62L⁺ T cells) might have superior anti-tumor effect than nCD8⁺CD62L⁺ T cells. Therefore, we investigated phenotypes, functions and the in vivo distribution of mCD8⁺CD62L⁺ T cells in tumor-bearing mice. We found that, while keeping the features of central memory T cells, the frequency of mCD8⁺CD62L⁺ T cell in the spleen of tumor-bearing mice was significantly higher than that the one of nCD8⁺CD62L⁺ T cell in naive mice. Moreover, we demonstrated that mCD8⁺CD62L⁺ T cells had higher proliferation rate and IFN-γ production than nCD8⁺CD62L⁺ T cells, in vitro. We performed adoptive transfer of mCD8⁺CD62L⁺ T cells into melanoma-bearing mice and tracked them in spleen, lymph nodes and in melanoma tissues. Our results show that mCD8⁺CD62L⁺ T cells had stronger in vivo anti-tumoral activity than nCD8⁺CD62L⁺ T cells. This study highlights the therapeutic potential of mCD8⁺CD62L⁺ T cells in the immunotherapy of melanoma and possibly other tumors.     

Characterization of CD8+CD57+ T cells in patients with acute myocardial infarction

Although T cells are known to be involved in the pathogenesis of coronary artery disease, it is unclear which subpopulation of T cells contributes to pathogenesis in acute myocardial infarction (MI). We studied the immunological characteristics and clinical impact of CD8⁺CD57⁺ T cells in acute MI patients. The frequency of CD57⁺ cells among CD8⁺ T cells was examined in peripheral blood sampled the morning after acute MI events. Interestingly, the frequency of CD57⁺ cells in the CD8⁺ T-cell population correlated with cardiovascular mortality 6 months after acute MI. The immunological characteristics of CD8⁺CD57⁺ T cells were elucidated by surface immunophenotyping, intracellular cytokine staining and flow cytometry. Immunophenotyping revealed that the CD8⁺CD57⁺ T cells were activated, senescent T cells with pro-inflammatory and tissue homing properties. Because a high frequency of CD8⁺CD57⁺ T cells is associated with short-term cardiovascular mortality in acute MI patients, this specific subset of CD8⁺ T cells might contribute to acute coronary events via their pro-inflammatory and high cytotoxic capacities. Identification of a pathogenic CD8⁺ T-cell subset expressing CD57 may offer opportunities for the evaluation and management of acute MI.     

CD8 T cell responses to influenza virus infection in aged mice

Influenza is one of the most common infectious diseases afflicting humans, particularly the elderly. The murine model has been widely employed for investigation of immunity to influenza virus infection. In this paper, we review the recent advances in understanding the diminished CD8 T cell immune response to influenza virus infection in aged mice. Possible mechanisms of impaired CD8 T cell responses with aging are addressed, including: (1) the role of dendritic cells (DCs); (2) the effect of age-associated changes in the T cell repertoire; and (3) the interactions with CD4 T cells, including T regulatory (Treg) cells and CD4 T helper cells. The aged murine model of the CD8 T cell response to influenza virus is helping to elucidate the mechanisms of immunosenescence which can lead to therapeutic improvements in the primary CD8 T cell response to new infections, as well as the development of new strategies for immunization to prevent influenza in the elderly.     

Features of peripheral CD8+CD57+ lymphocytes in patients with autoimmune hemolytic anemia

Autoimmune hemolytic anemia (AIHA) is an acquired condition characterized by the presence of autoantibodies recognizing erythrocyte-related antigens. Several components of the immune system are involved in disease pathogenesis. Among them, as for other autoimmune disorders, a role for specific CD8⁺CD57⁺ regulatory cells subset could be hypothesized. We evaluated this lymphocyte subset by flow cytometry in 18 AIHA patients randomly selected in a retrospective population of 29 cases. Secondary forms were observed in 65.5% of cases, whereas frequencies of warm, cold, mixed, and atypical forms were similar. Cold agglutinins and cryoglobulins tested positive in 44.8% and 10.3% of cases, respectively. These patients exhibited a higher frequency of peripheral vascular symptoms (odds ratio?=?8.2, p?=?.04) and complement consumption (odds ratio?=?7.2, p?=?.02). Frequency of CD8⁺CD57⁺ cells resulted significantly higher in AIHA patients than in control group (17.0?±?15.8% vs 8.2?±?5.0%, p?=?.04). Regardless of therapeutic schedule, patients with partial or no response to therapy (8/18) showed higher frequencies of CD8⁺CD57⁺ cells as compared with controls (23.6?±?21.3% vs 8.9?±?4.9%, p?=?.01), whereas 10/18 complete responders (CR) showed lower levels of CD8⁺CD57⁺ cells (11.7?±?6.9%, p?=?.11). CR and controls showed similar values (p?=?.24). This study suggests that monitoring this lymphocyte subset before and after treatment administration might have a prognostic value. Moreover, CD8⁺CD57⁺ cells may represent a possible therapeutic target to restore the normal balance between lymphocyte populations.     

巨细胞病毒感染C57BL/6小鼠诱导NK细胞免疫应答的模型研究

目的:研究小鼠巨细胞病毒(murine cytomegalovirus,MCMV)感染C57BL/6小鼠诱导自然杀伤(natural killer,NK)细胞免疫应答的最佳剂量和最佳时间。方法:分别根据剂量和时间效应进行分组,剂量效应：无特定病原体( specific pathogen free,SPF)级8周龄C57...     

CD8 lymphocytosis in primary cytomegalovirus (CMV) infection of allograft recipients: expansion of an uncommon CD8+ CD57- subset and its progressive replacement by CD8+ CD57+ T cells.

Allograft recipients undergoing cytomegalovirus infection present increased proportions of circulating CD8+ lymphocytes. A longitudinal study of 11 kidney and five liver allograft recipients with primary CMV infection but no other etiological factor of graft dysfunction revealed selective imbalances of peripheral blood CD8+ T cell subsets. Initially, CMV viraemia is associated with elevated CD8+bright T cell numbers and T cell activation. Activation markers fall to normal when viral cultures become negative (before the end of the first month). During the second to sixth month, most (12/16) patients keep up high CD8+ T cell counts (1050-2900 CD8+ cells/mm3), comprising an uncommon CD8+ T cell subset, as 45-73% of CD8+bright lymphocytes were CD3+ and TCR alpha beta+, but were not stained by anti-CD28, CD11b, CD16, CD56, and CD57 antibody. Unexpectedly, CD8+CD57+ T cells, a hallmark of CMV infection, do not appear until the second to sixth month of primary CMV infection, and their numbers increase progressively thereafter. They become the predominant CD8+ T cell subset after 6 months of infection and their persistence for several (up to 4) years is strongly correlated (r = 0.87) with expansion of CD8+ cells. By analysis with MoAbs, there was no bias towards the use of particular TCR-V beta gene families at any time of primary CMV infection. Persistence of CD8 lymphocytosis is thus directly related to the rate of expansion of an uncommon CD8+CD57- subset and its progressive replacement by CD8+CD57+ T cells that are chronically elicited by CMV.     

CD4+CD25+ T regulatory cells inhibit cytotoxic activity of T CD8+ and NK lymphocytes in the direct cell-to-cell interaction

There are reports suggesting an influence of CD4(+)CD25(+) T regulatory cells (Treg) on cytotoxic lymphocytes. The aim of the study was to evaluate such an influence. Cytotoxic activity was examined in the cultures of peripheral blood mononuclear cells (PBMC) as well as in the cultures of separate T CD8(+) or NK cells mixed with Treg and other subpopulations of PBMC. We found that the production of IFNgamma, perforin and cytotoxic activity of T CD8(+) or NK cells were decreased in the presence of Treg, however, the percentage of conjugates formed by cytotoxic cells with target cells during cytotoxic reaction was decreased only in the cultures of T CD8(+) cells. Inhibition of the cytotoxic reactions in the presence of Treg cells was found to be associated with the generation of conglomerates formed by CD4(+)CD25(+) and the cytotoxic cells, as observed under the fluorescence microscope. Treg produced IL10 when mixed with the cytotoxic lymphocytes, however, an addition of anti-IL10 mAb into the cultures did not affect the results. It is concluded that Treg were able to inhibit both T CD8+ and NK lymphocyte cytotoxic activities in a direct cell-to-cell interaction. Treg decreased the number of T CD8+ cells attached to the target cells, while the mechanism underlying a decrease in NK cytotoxicity remained unclear.     

Anomalies of the CD8+ T cell pool in haemochromatosis: HLA-A3-linked expansions of CD8+CD28− T cells

The present study consists of a phenotypic and functional characterization of peripheral blood T lymphocytes in a group of 21 patients with hereditary haemochromatosis (HH), an MHC class I-linked genetic disease resulting in iron overload, and a group of 30 healthy individuals, both HLA-phenotyped. The HH patients studied showed an increased percentage of CD8⁺ CD28⁻ T cells with a corresponding reduction in the percentage of CD8⁺ CD28⁺ T cells in peripheral blood relative to healthy blood donors. No anomalies of CD28 expression were found in the CD4⁺ subset. The presence of the HLA-A3 antigen but not age accounted for these imbalances. Thus, an apparent failure of the CD8⁺ CD28⁺ T cell population ‘to expand’, coinciding with an ‘expansion’ of CD8⁺ CD28⁻ T cells in peripheral blood of HLA-A3⁺ but not HLA-A3⁻ HH patients was observed when compared with the respective HLA-A3-matched control group. A significantly higher percentage of HLA-DR⁺ but not CD45RO⁺ cells was also found within the peripheral CD8⁺ T cell subset in HH patients relative to controls. Phytohaemagglutinin (PHA) stimulation of peripheral blood mononuclear cells (PBMC) for 5 days showed: (i) that CD8⁺ CD28⁺ T cells both in controls and HH were able to expand in vitro; (ii) that CD8⁺ CD28⁻ T cells decreased markedly after activation in controls but not in HH patients. Moreover, functional studies showed that CD8⁺ cytotoxic T lymphocytes (CTL) from HH patients exhibited a diminished cytotoxic activity (approx. two-fold) in standard ⁵¹Cr-release assays when compared with CD8⁺ CTL from healthy controls. The present results provide additional evidence for the existence of phenotypic and functional anomalies of the peripheral CD8⁺ T cell pool that may underlie the clinical heterogeneity of this iron overload disease. They are of particular relevance given the recent discovery of a novel mutated MHC class I-like gene in HH.     

T cell redistribution kinetics after secondary infection of BALB/c mice with respiratory syncytial virus.

BALB/c mice were infected intranasally with live respiratory syncytial virus (RSV) and reinfected 4 weeks later. At regular intervals thereafter groups of animals were killed and T cell subsets were determined in blood, spleen and bronchoalveolar lavage (BAL) with flow cytometry employing T cell subset-specific MoAbs. Total lymphocyte counts in the peripheral blood decreased 1-3 days after infection, returning to preinfection levels on day 8 (P = 0.0111). Simultaneously, a marked increase of lymphocytes was noted in the BAL, reaching a maximum at day 8 (P < 0.0001). Both CD4+ and CD8+ T cells decreased in the blood on day 1-3 (P < 0.0097 and P = 0.003 respectively), and increased in the BAL progressively towards a maximum at day 8 (P < 0.0001). In BAL, CD4+ cells increased 35-fold and CD8+ cells 27-fold during the first week after reinfection. On the other hand, in the spleen a significant decline of CD4+ and CD8+ cells was noted 1 day post-infection (P = 0.0002). It is concluded that a strong T cell redistribution response among systemic and mucosal tissues occurs after reinfection with RSV. The kinetics of this response differ both quantitatively and qualitatively from the T cell response after primary infection. The magnitude of cell traffic is more pronounced in blood, spleen and BAL than after primary infection. CD4+ T cells are more intensively distributed to the lungs than after primary infection.     

CD8+ CD28- and CD8+ CD57+ T cells and their role in health and disease

Chronic antigenic stimulation leads to gradual accumulation of late-differentiated, antigen-specific, oligoclonal T cells, particularly within the CD8(+) T-cell compartment. They are characterized by critically shortened telomeres, loss of CD28 and/or gain of CD57 expression and are defined as either CD8(+) CD28(-) or CD8(+) CD57(+) T lymphocytes. There is growing evidence that the CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell population plays a significant role in various diseases or conditions, associated with chronic immune activation such as cancer, chronic intracellular infections, chronic alcoholism, some chronic pulmonary diseases, autoimmune diseases, allogeneic transplantation, as well as has a great influence on age-related changes in the immune system status. CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell population is heterogeneous and composed of various functionally competing (cytotoxic and immunosuppressive) subsets thus the overall effect of CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell-mediated immunity depends on the predominance of a particular subset. Many articles claim that CD8(+) CD28(-) (CD8(+) CD57(+)) T cells have lost their proliferative capacity during process of replicative senescence triggered by repeated antigenic stimulation. However recent data indicate that CD8(+) CD28(-) (CD8(+) CD57(+)) T cells can transiently up-regulate telomerase activity and proliferate under certain stimulation conditions. Similarly, conflicting data is provided regarding CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell sensitivity to apoptosis, finally leading to the conclusion that this T-cell population is also heterogeneous in terms of its apoptotic potential. This review provides a comprehensive approach to the CD8(+) CD28(-) (CD8(+) CD57(+)) T-cell population: we describe in detail its origins, molecular and functional characteristics, subsets, role in various diseases or conditions, associated with persistent antigenic stimulation.     

Two-year follow-up of Helicobacter pylori infection in C57BL/6 and Balb/cA mice

Helicobacter pylori infection is associated with chronic gastritis, peptic ulcer disease, gastric adenocarcinoma and MALT lymphoma. We previously found high-grade lymphoma after 13 months' H. pylori infection in C57BL/6 mice. In this study we followed H. pylori infection by three different isolates in C57BL/6 and Balb/cA mice for 23 months. Six-week-old C57BL/6 and Balb/cA mice were infected with H. pylori strains 119p (CagA+, VacA+), SS1 (CagA+, VacA+) and G50 (CagA-, VacA-). Mice were followed at 2 weeks, 10 weeks and 23 months post-inoculation (p.i.) by culture, histopathology and serology. Strain G50 was only reisolated from mice 2 weeks p.i. There was no difference in colonization between strain 119p and SS1 at 10 weeks p.i., whereas SS1 gave 100% colonization versus 119p gave 50% 23 months p.i. Interestingly, the inflammation score was higher in mice infected with strain 119p than with SS1 10-week p.i., and there were lymphoepithelial lesions in mice infected with strain 119p and G50 but not with SS1 at 23 months post-infection. Eight mice infected with strains 119p and G50 developed gastric lymphoma (grade 5 and 4). One C57BL/6 mouse infected with strain 119p developed hepatocellular carcinoma after 23 months. Immunoblot showed specific bands of 26-33 kDa against H. pylori in infected mice, and two mice infected with strain SSI reacted with antibodies to the 120 kDa CagA toxin. Conclusion: A reproducible animal model for H. pylori-induced lymphoma and possibly hepatocellular carcinoma is described. Strain diversity may lead to different outcomes of H. pylori infection.     

Functional roles for T cell CD40 in infection and autoimmune disease: The role of CD40 in lymphocyte homeostasis

CD40 stimulation on monocytes/macrophages, dendritic cells, and B-lymphocytes has been the subject of much study. It is well recognized that activation of CD40 on antigen presenting cells by its ligand, CD154, expressed on T-lymphocytes, contributes to the pro-inflammatory response necessary for eradication of infection, yet pathological in autoimmunity. However, there is evidence that CD40 is also expressed on T-lymphocytes and can act as a costimulatory molecule. While the exact role of CD40 on CD8 T cells remains controversial, it does appear to contribute to the adaptive immune response against infection. CD40 on CD4 T cells, on the other hand, plays a functional role in the autoimmune disease process. Further dissection of the exact nature and role of CD40 in T cell activation could lead the way to more effective vaccines and novel therapeutics for autoimmune diseases.     

High-avidity CD8+ T cells

The primary goal of vaccination is the establishment of protective immunity. Thus there has been significant effort put toward the identification of attributes of the immune response that are associated with optimal protection. Although the number of virus-specific cells elicited is unquestionably important, recent studies have identified an additional parameter, functional avidity, as critical in determining the efficiency of viral clearance. T-cell avidity is a measure of the sensitivity of a cell to peptide antigen. High-avidity cells are those that can recognize antigen-presenting cells (APC) bearing very low levels of peptide antigen, whereas low-avidity cells require much higher numbers of peptide major histocompatibility complex (MHC) complexes in order to become activated or exert effector function. We are only now beginning to gain insights into the molecular control of avidity and the signals required for the optimal activation, expansion, and retention of high-avidity cells in vivo. This review summarizes the current knowledge regarding CD8⁺ T-cell avidity and explores some of the important issues that are, as of yet, unresolved.     

Analysis of the immune response of Hantaan virus nucleocapsid protein-specific CD8+ T cells in mice

The major histocompatibility complex (MHC) class-I restricted epitope of Hantaan virus nucleocapsid protein (N) was identified using overlapping peptides and BALB/c mice. Using the MHC tetramer derived from the epitope, we found that the level of N-specific CD8(+) T cells increased to approximately 20% of all antigen-specific CD8(+) T cells in a mouse model of transient infection. However, N-specific CD8(+) T cells were undetectable in a mouse model of persistent infection, both in the persistently infected phase and in the convalescent phase. Levels of CD8(+) T cells producing interferon-gamma were weak in both the acute and convalescent phases in the persistently infected model. These results indicate that hantavirus strongly suppresses the production of N-specific CD8(+) T cells throughout the course of infection in persistently infected mice. Moreover, N-specific CD8(+) T cells were not effective in recovering persistently infected mice, despite the existence of abundant N antigen in vivo.     

Abnormality in the cerebellar folial pattern of C57BL/6J mice

The characteristic folial pattern of the mouse cerebellum is formed during postnatal development. We observed this process in C57BL/6J (B6) mice in detail, and found an abnormal folial pattern in a specific region (lobules VIII and IX of the vermis) in a substantial number of B6 mice. The frequency of this abnormality increased during postnatal development and reached 55% in the adult. Thus, the present study showed an abnormality in the cerebellar folial pattern of B6 mice, a mouse widely used in knockout studies, and called for caution in the phenotypic analysis of knockout mice of the B6 genetic background.     

Impaired CD4 and CD8 T cell phenotype and reduced chemokine secretion in recent-onset type 1 diabetic children

Although the role of the T cell-mediated autoimmune reaction in type 1 diabetes (T1D) is conclusive, studies including data from human circulating CD4(+) and CD8(+) lymphocytes subsets during the disease onset and posterior development are scarce. Further, chemokines and chemokine receptors are key players in the migration of pathogenic T cells into the islets of non-obese diabetic mice developing T1D, but few studies have investigated these markers in human T1D patients. We studied the expression of T helper 1 (Th1)- and Th2-associated chemokine receptors, and the two isoforms of CD45 leucocyte antigen on CD4(+) and CD8(+) lymphocytes from T1D and healthy children, as well as the secretion of chemokines in cell supernatants in peripheral blood mononuclear cells. Our results showed increased expression of CCR7 and CD45RA and reduced CD45RO on CD8(+) cells among recent-onset T1D patients. The percentages of CD4(+) cells expressing CXC chemokine receptor 3 (CXCR3), CXCR6 and CCR5, and the secretion of interferon-gamma-induced protein-10, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta was lower among diabetics. Low expression of Th1-associated receptors and secretion of chemokines, together with an increased amount of CD8(+) cells expressing CD45RA and CCR7 in T1D patients therefore might represent suboptimal Th function in T1D, leading to impaired T cytotoxic responses or alternatively reflect a selective recruitment of Th1 cells into the pancreas.