Multi-resolution characterization of molecular taxonomies in bulk and single-cell transcriptomics data

As high-throughput genomics assays become more efficient and cost effective, their utilization has become standard in large-scale biomedical projects. These studies are often explorative, in that relationships between samples are not explicitly defined a priori, but rather emerge from data-driven discovery and annotation of molecular subtypes, thereby informing hypotheses and independent evaluation. Here, we present K2Taxonomer, a novel unsupervised recursive partitioning algorithm and associated R package that utilize ensemble learning to identify robust subgroups in a 'taxonomy-like' structure. K2Taxonomer was devised to accommodate different data paradigms, and is suitable for the analysis of both bulk and single-cell transcriptomics, and other '-omics', data. For each of these data types, we demonstrate the power of K2Taxonomer to discover known relationships in both simulated and human tissue data. We conclude with a practical application on breast cancer tumor infiltrating lymphocyte (TIL) single-cell profiles, in which we identified co-expression of translational machinery genes as a dominant transcriptional program shared by T cells subtypes, associated with better prognosis in breast cancer tissue bulk expression data.

Isolation and immunophenotyping by flow cytometry of canine peripheral blood and intraepithelial and lamina propria duodenal T lymphocytes

The gut associated lymphoid tissue (GALT) effector sites play a crucial role on the pathogenesis of many immune-mediated gastrointestinal diseases. The lymphocytes at these effector sites are principally T cells which present important morphological, phenotypical and functional differences. Flow cytometry (FC) is one of the most commonly used techniques to characterize intestinal lymphocytes in human and animal models. Published studies with a focus on dogs for intraepithelial lymphocytes (IEL) immunophenotyping exist in very limited numbers. Moreover, no lamina propria lymphocytes (LPL) isolation protocols in the canine species have been described for FC evaluation. In addition to immune intestinal dysregulation, imbalances in the peripheral blood immune system have been described in both human and animal gastrointestinal disorders. The aim of this study was to provide a protocol for canine IEL and LPL isolation for FC immunophenotyping of T cells subsets. Specifically, T helper, T cytotoxic, activated Th and Tc lymphocytes, regulatory, double negative, double positive, IFN-γ and IL-4 producing T cells, and to compare their respective populations between these effector sites and with the blood stream compartment in healthy dogs. The potential relationship of these cells distributions with age, sex and breed was also evaluated. This study included sixteen healthy dogs of different sexes and breeds with a mean age of 4.55 ± 2.93 years old. The selected protocols for the three immune compartments showed proper cell yield, purity, viability, and the absence of phenotypic and functional disturbances. Histologically, an adequate separation of the duodenal epithelium from the lamina propria was also observed. All the proposed T cells subsets were identified in the three immune compartments studied, showing some statistically significant differences in their distributions at these locations that highlight the importance of their individual evaluation. This study provides an adequate method for canine small intestine IEL and LPL isolation for FC immunophenotyping and is key for future studies on the gastrointestinal immune system associated with different canine diseases.

Characterization of membrane-bound IL-22+ T cell subsets in HIV-1 patients coinfected with Mycobacterium tuberculosis

BACKGROUND

Previously, we have found that IL-22 could be not only secreted outside of cells, but also highly expressed on the T cells membrane in HIV-1 negative patients with tuberculosis (TB). However, the study on membrane-bound IL-22+ cells of HIV-1 infected patients is rare. Therefore, we investigated antigen-specific membrane-bound IL-22+ T cell subsets in Mycobacterium tuberculosis (M.tb) coinfection of HIV-1 infected individuals.

METHODS

A case-control study that enrolled 74 HIV-1 infected participants was carried out, including HIV-1 monoinfection (HIV+TB-, n = 43), HIV-1 infected patients with latent TB (HIV+LTB, n = 18) and HIV-1 coinfected patients with active TB (HIV+TB+, n = 13). We made use of an IFN-γ release assay (IGRA) to screen LTB individuals. Purified protein derivative (PPD) and phosphoantigen (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) were used as specific-stimulators to detect the levels of peripheral blood membrane-bound IL-22+ T cell subsets via cell surface staining and flow cytometry among three groups.

RESULTS

An approximate rate of 24.3% (n = 18 out of 74) of latent M.tb infection among HIV-1 positive population in Eastern China. Interestingly, HMBPP-specific CD3+Vγ2+ T cells were impaired in HIV+TB+patients compared with HIV+LTB patients (P < 0.05). Furthermore, increases of PPD-specific and HMBPP-specific membrane-bound IL-22+ T cell subsets including CD3+, CD3+CD4+ and CD3+Vγ2+ T cells were observed in HIV+TB+group rather than HIV+LTB groups (all P < 0.05).

CONCLUSION

Antigen-specific membrane-bound IL-22+ T cells were highly expressed in M.tb coinfection of HIV-1 infected individuals, and may play an important role in anti-TB immune response during coinfection with HIV-1.

Phenotype and molecular signature of CD8+ T cell subsets in T cell- mediated rejections after kidney transplantation

We investigated the phenotype and molecular signatures of CD8+ T cell subsets in kidney-transplant recipients (KTRs) with biopsy-proven T cell-mediated rejection (TCMR). We included 121 KTRs and divided them into three groups according to the pathologic or clinical diagnosis: Normal biopsy control (NC)(n = 32), TCMR (n = 50), and long-term graft survival (LTGS)(n = 39). We used flowcytometry and microarray to analyze the phenotype and molecular signatures of CD8+ T cell subsets using peripheral blood from those patients and analyzed significant gene expressions according to CD8+ T cell subsets. We investigated whether the analysis of CD8+ T cell subsets is useful for predicting the development of TCMR. CCR7+CD8+ T cells significantly decreased, but CD28nullCD57+CD8+ T cells and CCR7-CD45RA+CD8+ T cells showed an increase in the TCMR group compared to other groups (p<0.05 for each); hence CCR7+CD8+ T cells showed significant negative correlations to both effector CD8+ T cells. We identified genes significantly associated with the change of CCR7+CD8+ T, CCR7-CD45RA+CD8+ T, and CD28nullCD57+CD8+ T cells in an ex vivo study and found that most of them were included in the significant genes on in vitro CCR7+CD8+ T cells. Finally, the decrease of CCR7+CD8+ T cells relative to CD28nullCD57+ T or CCR7-CD45RA+CD8+ T cells can predict TCMR significantly in the whole clinical cohort. In conclusion, phenotype and molecular signature of CD8+ T subsets showed a significant relationship to the development of TCMR; hence monitoring of CD8+ T cell subsets may be a useful for predicting TCMR in KTRs.

Unravelling the heterogeneity and dynamic relationships of tumor-infiltrating T cells by single-cell RNA sequencing analysis

T cells are crucial for the success of immune-based cancer therapy. Reinvigorating antitumor T cell activity by blocking checkpoint inhibitory receptors has provided clinical benefits for many cancer patients. However, the efficacy of these treatments varies in cancer patients and the mechanisms underlying these diverse responses remain elusive. The density and status of tumor-infiltrating T cells have been shown to positively correlate with patient response to checkpoint blockades. Therefore, further understanding of the heterogeneity, clonal expansion, migration, and effector functions of tumor-infiltrating T cells will provide fundamental insights into antitumor immune responses. To this end, recent advances in single-cell RNA sequencing technology have enabled profound and extensive characterization of intratumoral immune cells and have improved our understanding of their dynamic relationships. Here, we summarize recent progress in single-cell RNA sequencing technology and current strategies to uncover heterogeneous tumor-infiltrating T cell subsets. In particular, we discuss how the coupling of deep transcriptome information with T cell receptor (TCR)-based lineage tracing has furthered our understanding of intratumoral T cell populations. We also discuss the functional implications of various T cell subsets in tumors and highlight the identification of novel T cell markers with therapeutic or prognostic potential.

IL-7-dependent compositional changes within the γδ T cell pool in lymph nodes during ageing lead to an unbalanced anti-tumour response

How the age-associated decline of immune function leads to increased cancer incidence is poorly understood. Here, we have characterised the cellular composition of the γδ T-cell pool in peripheral lymph nodes (pLNs) upon ageing. We find that ageing has minimal cell-intrinsic effects on function and global gene expression of γδ T cells, and γδTCR diversity remains stable. However, ageing alters TCRδ chain usage and clonal structure of γδ T-cell subsets. Importantly, IL-17-producing γδ17 T cells dominate the γδ T-cell pool of aged mice-mainly due to the selective expansion of Vγ6+ γδ17 T cells and augmented γδ17 polarisation of Vγ4+ T cells. Expansion of the γδ17 T-cell compartment is mediated by increased IL-7 expression in the T-cell zone of old mice. In a Lewis lung cancer model, pro-tumourigenic Vγ6+ γδ17 T cells are exclusively activated in the tumour-draining LN and their infiltration into the tumour correlates with increased tumour size in aged mice. Thus, upon ageing, substantial compositional changes in γδ T-cell pool in the pLN lead to an unbalanced γδ T-cell response in the tumour that is associated with accelerated tumour growth.

Distinct phenotype of CD4+ T cells driving celiac disease identified in multiple autoimmune conditions

Combining HLA-DQ-gluten tetramers with mass cytometry and RNA sequencing analysis, we find that gluten-specific CD4+ T cells in the blood and intestines of patients with celiac disease display a surprisingly rare phenotype. Cells with this phenotype are also elevated in patients with systemic sclerosis and systemic lupus erythematosus, suggesting a way to characterize CD4+ T cells specific for disease-driving antigens in multiple autoimmune conditions.

Lymphocyte and monocyte subpopulations in severe aortic stenosis at the time of surgical intervention

INTRODUCTION

Aortic stenosis (AS) is the most common acquired valvular heart disease in adults. Immune system involvement becomes evident during AS development. We sought to investigate the role of different circulating lymphocyte and monocyte subpopulations, with focus on CD4⁺CD8⁺ and natural killer T (NKT) cells, in AS.

MATERIAL AND METHODS

Blood samples and aortic valves were obtained from patients undergoing elective aortic valve surgery. Valves were dissected and underwent genetic analyses and calcium content assessment. Lymphocytes and monocytes subsets were assessed by flow cytometry.

RESULTS

Thirty-eight AS patients were studied. Maximal transvalvular pressure gradient (PG_max) as well as mean transvalvular pressure gradient (PG_mean) correlated with the CD4⁺CD8⁺ lymphocyte count (r=0.35, P=.03 and r=0.43, P=.006, respectively) and fraction (r=0.43, P=.007 and r=0.48, P=.002, respectively). PG_max and PG_mean correlated with CD16⁺CD56⁺CD3⁺ NKT cell count (r=0.39, P=.01 and r=0.43, P=.007, respectively) and fraction (r=0.49, P=.002 and r=0.47, P=.003, respectively). The classical monocyte subpopulation increased after the surgery by 68% (P<.0001). Patients after mini-sternotomy surgery had 47% lower nonclassical monocyte counts than those with full-sternotomy (P=.03). Patients treated with statins had significantly lower postoperative levels of both classical (-25%, P=.04) and nonclassical monocytes (-37%, P=.004) than nontreated individuals.

CONCLUSIONS

In patients with severe isolated AS, CD4⁺CD8⁺ T cells and CD16⁺CD56⁺CD3⁺ NKT cells are associated with AV pressure gradients. Postoperative monocyte levels are affected by procedure invasiveness and use of statins.

Anti-Anisakis sp. antibodies in serum of healthy subjects. Relationship with αβ and γδ T cells

Anisakiosis is nowadays one of the nematodoses more prevalent in Spain, with rates that oscillate between 0.43% in Galicia (N.W. Spain), and 15.7% and 22.1% in inland and southern regions, respectively. Likewise, it has been proved that Anisakis larvae have developed mechanisms to modulate the dichotomy of the host immune response for their own benefit. The experimental hypothesis of the present study was that Anisakis sp. larval products can be mediators of immune suppression and induce changes on the populations of αβ+ and γδ+ T cells. In the present study we determined the levels of anti-Anisakis antibodies in the serum of healthy people, and their relationship with the B and T cell subsets. Levels of anti-Anisakis antibodies (Ig's, IgG, IgM, IgA and IgE) were measured by ELISA, while B and T cell subsets were studied by flow cytometry. Cells were labelled with monoclonal antibodies against CD45, CD4, CD8, CD56, CD3, CD19, TCRαβ and TCRγδ. All the specific isotypes studied were negatively correlated with NKT cell rates with the exception of IgG. A previous contact with Anisakis was related to a decrease in CD56+αβ+ and all γδ+ T cell subsets. The CD3+γδ+ population was lower in the group of subjects that showed IgA anti-Anisakis. We observed an inverse correlation among αβ-γδ NKT cells and anti-Anisakis sp. antibodies. CD3+CD56+ cells showed a significant decrease in the group of anti-Anisakis positive subjects. This fact was especially significant with CD3+CD56+γδ+ cells in the case of the anti-Anisakis IgA positive group.

Differential effects of Cytomegalovirus carriage on the immune phenotype of middle-aged males and females

The elderly population is more susceptible to infections as a result of an altered immune response, commonly referred to as immunosenescence. Cytomegalovirus (CMV)-infection associated changes in blood lymphocytes are known to impact this process, but the interaction with gender remains unclear. Therefore, we analysed the effects and interaction of gender and CMV on the absolute numbers of a comprehensive set of naive and memory T- and B-cell subsets in people between 50 and 65 years of age. Enumeration and characterisation of lymphocyte subsets by flow cytometry was performed on fresh whole blood samples from 255 middle-aged persons. CMV-IgG serostatus was determined by ELISA. Gender was a major factor affecting immune cell numbers. CMV infection was mainly associated with an expansion of late-differentiated T-cell subsets. CMV+ males carried lower numbers of total CD4+, CD4+ central memory (CM) and follicular helper T-cells than females and CMV- males. Moreover, CMV+ males had significantly lower numbers of regulatory T (Treg)-cells and memory B-cells than CMV+ females. We here demonstrate an interaction between the effects of CMV infection and gender on T- and B-cells in middle-aged individuals. These differential effects on adaptive immunity between males and females may have implications for vaccination strategies at middle-age.

Decreased memory B cells and increased CD8 memory T cells in blood of breastfed children: the generation R study

Background

Breastfeeding provides a protective effect against infectious diseases in infancy. Still, immunological evidence for enhanced adaptive immunity in breastfed children remains inconclusive.

Objective

To determine whether breastfeeding affects B- and T-cell memory in the first years of life.

Methods

We performed immunophenotypic analysis on blood samples within a population-based prospective cohort study. Participants included children at 6 months (n=258), 14 months (n=166), 25 months (n=112) and 6 years of age (n=332) with both data on breastfeeding and blood lymphocytes. Total B- and T-cell numbers and their memory subsets were determined with 6-color flow cytometry. Mothers completed questionnaires on breastfeeding when their children were aged 2, 6, and 12 months. Multiple linear regression models with adjustments for potential confounders were performed.

Results

Per month continuation of breastfeeding, a 3% (95% CI -6, -1) decrease in CD27+IgM+, a 2% (95 CI % -5, -1) decrease in CD27+IgA+ and a 2% (95% CI -4, -1) decrease in CD27-IgG+ memory B cell numbers were observed at 6 months of age. CD8 T-cell numbers at 6 months of age were 20% (95% CI 3, 37) higher in breastfed than in non-breastfed infants. This was mainly found for central memory CD8 T cells and associated with exposure to breast milk, rather than duration. The same trend was observed at 14 months, but associations disappeared at older ages.

Conclusions

Longer breastfeeding is associated with increased CD8 T-cell memory, but not B-cell memory numbers in the first 6 months of life. This transient skewing towards T cell memory might contribute to the protective effect against infectious diseases in infancy.

Th9 cell development requires a BATF-regulated transcriptional network

T helper 9 (Th9) cells are specialized for the production of IL-9, promote allergic inflammation in mice, and are associated with allergic disease in humans. It has not been determined whether Th9 cells express a characteristic transcriptional signature. In this study, we performed microarray analysis to identify genes enriched in Th9 cells compared with other Th subsets. This analysis defined a transcriptional regulatory network required for the expression of a subset of Th9-enriched genes. The activator protein 1 (AP1) family transcription factor BATF (B cell, activating transcription factor–like) was among the genes enriched in Th9 cells and was required for the expression of IL-9 and other Th9-associated genes in both human and mouse T cells. The expression of BATF was increased in Th9 cultures derived from atopic infants compared with Th9 cultures from control infants. T cells deficient in BATF expression had a diminished capacity to promote allergic inflammation compared with wild-type controls. Moreover, mouse Th9 cells ectopically expressing BATF were more efficient at promoting allergic inflammation than control transduced cells. These data indicate that BATF is a central regulator of the Th9 phenotype and contributes to the development of allergic inflammation.

Lipid presentation by human CD1 molecules and the diverse T cell populations that respond to them

CD1 molecules bind and present lipid-based antigens to T cells. Humans express both Group 1 (CD1a, CD1b and CD1c) and Group 2 (CD1d) CD1 molecules with nonredundant functions in the human immune response. Studies of Group 1 CD1 molecules and the T cells that respond to them have lagged behind Group 2 due to the lack of a suitable model system. However, recent work has thrust the Group 1 CD1s into the limelight, revealing their importance in tissue surveillance and microbial defense. Here I review recent advances in Group 1 CD1 lipid presentation, the T cell populations that respond to them and the role of CD1 molecules in engagement of human γδ T cells.

Effector and regulatory T cells in patients with acute optic neuritis

OBJECTIVE

Optic neuritis (ON) is an autoimmune acute demyelinating disease of the optic nerve and may occur in patients with confirmed multiple sclerosis (MS) or as a clinically isolated syndrome. T lymphocytes play a central role in the pathogenesis of MS. The phenotype of different T cell subsets is usually characterized by the expression of distinct cell surface receptors such as CD45RA, CD45RO, CCR7, CD27 and CD28. The aim of this study was to characterize the phenotype of distinct subsets of CD4 and CD8 T cells in patients with isolated ON.

METHODS

CD4 and CD8 T cell subsets were characterized by flow cytometry in fresh peripheral blood and cerebrospinal fluid (CSF) samples using the surface markers CD27, CD25, CD45RA, CD45RO and intracellular FOXP3. The T cell subsets expressed in patients with acute ON (n = 64; symptom onset of ON within the preceding 28 days) were compared to those of a gender- and age-matched healthy control (HC) group (n = 32).

RESULTS

Both CD4+ and CD8+ naïve T cells in the ON group were significantly reduced in the CSF. In contrast, most of the intermediate-stage and late effector CD4+ and CD8+ T cell subsets as well as the CD4+ T regulatory cells were expressed in ON patients, though not at all in the CSF of the HC group.

CONCLUSION

These results add important evidence for inflammatory and regulatory activity in ON and early MS.

[The latest TH17 lymphocyte in the family of T CD4+ lymphocytes]

In recent years the T CD4+ lymphocyte family has grown. In the initial two components TH1 and TH2 lymphocytes were added the TH17 lymphocyte and T cell regulator (Treg). Under the influence of transforming growth factor β, interleukin 6 (IL6), IL21 and IL23, the naive lymphocyte T CD4+ differentiates in TH17. Currently, the TH17 is recognized as the leading actor of local inflammation through the pro-inflammatory cytokines (interleukins 17, 21, 22) that secretes and the expansion and recruitment of neutrophils that leads. Therefore, it is involved in chronic inflammatory processes, autoimmune diseases (rheumatoid arthritis, systemic lupus erythematosus), allergy and rejection of allogeneic transplants. TH17 lymphocyte opens up new therapeutic prospects for these pathologies.

[Scleroderma related to specific immunotherapy. A report of a case]

It has been described two main phenotypes of helper T cells. On activation, the immune system develops the most effective Th response. Whereas Th1 cells promote cell-mediate immunity against intracellular pathogens and an over expression could favor autoimmune diseases; Th2 cells develop humoral immunity against extracellular pathogens promoting allergic response. Normally, the two profiles coexist in the same individual with different grades of expression. Recently, it has been described a new subset: Th17, which is related to tissue injury in autoimmune diseases. Then, allergic and autoimmune diseases result from an unbalanced response of the immune system. Allergen-specific immunotherapy is the only curative treatment of a specific allergy, which leads to a life-long tolerance against allergens. There are no controlled studies about the effectiveness or risks associated with allergen-specific immunotherapy in patients with autoimmune disorders. On the other hand, scleroderma is an autoimmune chronic systemic disorder of unknown etiology characterized by excess collagen deposition in the skin and viscera, along with vascular injury. We report a girl with allergic asthma and with a second degree family history of systemic sclerosis who developed localized scleroderma during allergen specific immunotherapy. Because allergy vaccination alter the balance between effector and regulatory T-cell populations, which regulate immune tolerance, a positive family history of autoimmunity in first or second degree, could be a contraindication for allergen-specific immunotherapy.

Cross-regulation between type I and type II NKT cells in regulating tumor immunity: a new immunoregulatory axis

Negative immunoregulation is a major barrier to successful cancer immunotherapy. The NKT cell is known to be one such regulator. In this study we explored the roles of and interaction between the classical type I NKT cell and the poorly understood type II NKT cell in the regulation of tumor immunity. Selective stimulation of type II NKT cells suppressed immunosurveillance, whereas stimulation of type I NKT cells protected against tumor growth even when responses were relatively skewed toward Th2 cytokines. When both were stimulated simultaneously, type II NKT cells appeared to suppress the activation in vitro and protective effect in vivo of type I NKT cells. In the absence of type I, suppression by type II NKT cells increased, suggesting that type I cells reduce the suppressive effect of type II NKT cells. Thus, in tumor immunity type I and type II NKT cells have opposite and counteractive roles and define a new immunoregulatory axis. Alteration of the balance between the protective type I and the suppressive type II NKT cell may be exploited for therapeutic intervention in cancer.

Regulation of T lymphocyte subsets

Patterns of cytokine secretion and functional differences distinguish T lymphocyte subsets. T lymphocyte subsets are also regulated differentially. Most established CD8+ lymphocyte clones secrete gamma-interferon (IFN-gamma) but not interleukin 2 (IL-2) or IL-4. Using murine T cells which express a transgenic, antigen-specific alpha/beta T cell receptor (TCR) specific for L(d) class I major histocompatibility complex antigen, we have found that CD8+ lymphocytes can be divided into functional subsets. Freshly isolated CD8+ T cells are not cytolytic, do not proliferate and do not proliferate and do not secrete cytokines. Stimulation of TCR alone does not induce cytokine secretion, but cells become responsive to exogenous IL-2 or IL-4. Stimulation of CD28 together with TCR induces secretion of IL-2 and IFN-gamma, and cells proliferate without exogenous cytokines. Proliferation is necessary for the development of cytolytic activity. If IL-4 is present during initial stimulation, IL-4 is secreted following restimulation. Upon stimulation, some IL-4-producing murine CD8+ T cell clones express CD40 ligand (CD40L), and they potentiate proliferation and immunoglobulin secretion by small resting B cells. Thus, the CD8+ T cell subsets T cytotoxic 1 (Tc1) and Tc2 are analogous to CD4+ T helper 1 (Th1) and Th2. IL-2 production by naive CD8+ cells requires co-stimulation. IL-4 production by CD8+ T cells requires the presence of IL-4 during initial stimulation. Some IL-4-producing CD8+ T cells express CD40L following TCR stimulation and provide help for B cells.

Basic science for the clinician 45: CD4+ T-cell subsets of probable clinical consequence

I have often said "blessed be the splitters, for they shall inherit the earth." By that I mean that it is only by studying carefully culled populations, approaching, but never quite reaching, homogeneity that we can ever gain real insights into rheumatologic diseases. Differentiating tuberculous from gouty from rheumatoid arthritis was a good start, and when Moll and Wright identified the seronegative spondyloarthropathies, we were on our way to establishing "splitters" as leaders. Predictably, once T cells were identified as different from B cells, the floodgates opened. Subsets galore were described, with more isolated populations in the T-cell family, but we are now finding heterogeneity in B-cell populations, as well, which has been discussed in a previous article in this series. But as for T cells... well, it has not been smooth sailing. I initially trained in a laboratory that was firmly committed to the proposition that there were within the CD8 population not only cytotoxic cells but also "suppressor cells." Problem is, no one could ever isolate the little buggers, and so the idea of a suppressor or regulatory subpopulation of CD8+ T cells went the way of the Edsel. As noted in a previous article in this series, T regulatory cells were finally identified but not within the CD8+ population. And there are other regulatory subsets within both CD4+ and CD8+ T-cells populations and even new effector and memory populations that can be identified by their surface markers and functions. It is high time to review some of them; some of these populations may be involved in the immunopathogenesis of our diseases and undoubtedly will shortly be targets of immunotherapeutics. Although previous articles in this series discussed some of these subsets, I thought expanding on what is known about another recently described subset and putting them all together in one review might be helpful.

Altered homeostasis of CD4(+) memory T cells in allogeneic hematopoietic stem cell transplant recipients: chronic graft-versus-host disease enhances T cell differentiation and exhausts central memory T cell pool

An increased risk of late infection is a serious complication after allogeneic hematopoietic stem cell transplantation (AHSCT), especially for recipients with defective CD4(+) T cell recovery. Although chronic graft-versus-host disease (cGVHD) negatively influences CD4(+) T cell reconstitution, the mechanisms leading to this defect are not well understood. We found that the proportion of CD27(-) CD4(+) T cells was remarkably increased in ASHCT recipients with cGVHD or with repetitive infectious episodes. Isolated CD27(-) CD4(+) T cells from ASHCT recipients had significantly shortened telomere length, displayed enhanced vulnerability to activation-induced cell death, and showed extremely reduced clonal diversity, when compared with CD27(-) CD4(+) T cells from healthy donors. Also, CD27(+) CD4(+) T cells from AHSCT recipients easily lost their expression of CD27 in response to antigen stimulation regardless of cGVHD status. Taken together, these data indicate that homeostasis of memory CD4(+) T cells from AHSCT recipients is altered, and that they easily transit into CD27(-) effector memory T cells. Increased in vivo T cell stimulation observed in recipients with cGVHD further promotes the transition to effector memory cells, a change that decreases the central memory CD4(+) T cell pool and consequently weakens the recipient's defense against persistently infecting pathogens.

Aging is associated with a rapid decline in frequency, alterations in subset composition, and enhanced Th2 response in CD1d-restricted NKT cells from human peripheral blood

NKT cells are important for initiating and regulating immune responses. We investigated the age-related changes in the CD1d-restricted semi-invariant NKT (iNKT) cells in peripheral blood of healthy adults. The iNKT cell frequency was 2.5- to 10.7-fold less in healthy elderly subjects (61 years and over) compared to the healthy young subjects (20-40 years, p<0.001). This age-related decline in iNKT cells was observed both in freshly isolated PBMC and in cultures where iNKT cells were enriched by alpha-GalCer stimulation using either the Valpha24/Vbeta11 TCR antibody pair or the CD1d-tetramer as the iNKT cell marker. The decline in frequency was associated with an alteration in the iNKT cell subset compositions: an increase in the proportion of CD4+ subset and a decrease in the proportion of CD4/CD8 double-negative (DN) subset. The age-related decline in iNKT cells and changes in subset composition were independent from the age-related changes of conventional T cells/T cell subsets. Additionally, there was a Th1 to Th2 shift in the cytokine response profile from iNKT cells with aging. We conclude that aging is associated with a significant decline in iNKT cell frequency in peripheral blood, accompanied with alterations in subset composition and cytokine response profile.

Four functionally distinct populations of human effector-memory CD8+ T lymphocytes

In humans, the pathways of memory and effector T cell differentiation remain poorly defined. We have dissected the functional properties of ex vivo effector-memory (EM) CD45RA-CCR7- T lymphocytes present within the circulating CD8+ T cell pool of healthy individuals. Our studies show that EM T cells are heterogeneous and are subdivided based on differential CD27 and CD28 expression into four subsets. EM(1) (CD27+CD28+) and EM(4) (CD27-CD28+) T cells express low levels of effector mediators such as granzyme B and perforin and high levels of CD127/IL-7Ralpha. EM(1) cells also have a relatively short replicative history and display strong ex vivo telomerase activity. Therefore, these cells are closely related to central-memory (CD45RA-CCR7+) cells. In contrast, EM(2) (CD27+CD28-) and EM(3) (CD27-CD28-) cells express mediators characteristic of effector cells, whereby EM(3) cells display stronger ex vivo cytolytic activity and have experienced larger numbers of cell divisions, thus resembling differentiated effector (CD45RA+CCR7-) cells. These data indicate that progressive up-regulation of cytolytic activity and stepwise loss of CCR7, CD28, and CD27 both characterize CD8+ T cell differentiation. Finally, memory CD8+ T cells not only include central-memory cells but also EM(1) cells, which differ in CCR7 expression and may therefore confer memory functions in lymphoid and peripheral tissues, respectively.

APC-derived cytokines and T cell polarization in autoimmune inflammation

T cell-mediated autoimmune diseases such as multiple sclerosis and rheumatoid arthritis are driven by autoaggressive Th cells. The pathogenicity of such Th cells has, in the past, been considered to be dictated by their cytokine polarization profile. The polarization of such effector T cells relies critically upon the actions of cytokines secreted by APCs. While Th1 polarization has long been associated with the pathogenesis of autoimmune diseases, recent data obtained in gene-targeted mice and the discovery of Th17 cell involvement in autoimmunity conflict with this hypothesis. In light of these recent developments, we discuss in this review the actions of APC-derived cytokines and their emerging roles in T cell polarization in the context of autoimmune inflammatory responses.

Invariant NKT and NKT-like lymphocytes: two different T cell subsets that are differentially affected by ageing

The expression on T lymphocytes of surface receptors that are characteristically expressed on NK cells has led to the definition of a T cell subset that has been termed Natural Killer T (NKT) cells. Thus NKT cells constitute a minor lymphocyte population that exhibits features of both T cells and NK cells. However, the term 'NKT cell' has been applied variably to cells that express a restricted T-cell receptor (TCR) that recognizes glycolipids (alpha-GalCer) presented by the MHC-like molecule CD1d and that express CD161, as well as populations of conventional CD8 T cells that show up-regulated expression of NK-cell markers. The CD1d restricted T cells have a semi-invariant TCR using the Valpha24Jalpha18 genes in humans (Valpha24Jalpha18 in mice) and are denominated invariant NKT (iNKT) cells. On the other hand mainstream T cells that express NK associated receptors (NKR) show a highly specialized effector memory phenotype and are frequently referred as NKT-like cells. These T lymphocyte subsets are differentially affected by ageing. Whereas human peripheral blood iNKT cells decrease with age, there is an increase in the percentage of peripheral blood NKT-like T lymphocytes.

Balancing tolerance and immunity: the role of dendritic cell and T cell subsets

The interaction between dendritic cells and T cells is crucial for the regulation of immunological tolerance and immunity. Although our understanding of the mechanisms responsible for these phenomena has advanced significantly in recent years, we are still lacking a fully integrated model of how dendritic cell phenotype correlates with function, and how complex interactions with multiple dendritic and T cell subpopulations shape the course of the immune response in vivo. In this review, we summarize the current state of knowledge in the field, highlighting the areas where further investigation is likely to advance our understanding of this fundamental immunological interaction.

Human natural killer T cells are heterogeneous in their capacity to reprogram their effector functions

Background

Natural killer T (NKT) cells are a subset of T cells that help potentiate and regulate immune responses. Although human NKT cell subsets with distinct effector functions have been identified, it is unclear whether the effector functions of these subsets are imprinted during development or can be selectively reprogrammed in the periphery.

Results

We found that neonatal NKT cells are predominantly CD4+ and express higher levels of CCR7 and CD62L and lower levels of CD94 and CD161 than adult CD4+ or CD4− NKT cell subsets. Accordingly, neonatal NKT cells were more flexible than adult CD4+ NKT cells in their capacity to acquire Th1- or Th2-like functions upon either cytokine-mediated polarization or ectopic expression of the Th1 or Th2 transcription factors T-bet and GATA-3, respectively. Consistent with their more differentiated phenotype, CD4- NKT cells were predominantly resistant to functional reprogramming and displayed higher cytotoxic function. In contrast to conventional T cells, neither the expression of CXCR3 nor the cytotoxic capacity of neonatal NKT cells could be reprogrammed.

Conclusions and Significance

Together, these results suggest that neonatal CD4+, adult CD4+, and adult CD4− NKT may represent unique states of maturation and that some functions of human NKT cells may be developmentally imprinted, while others are acquired similar to conventional T cell subsets during peripheral maturation and differentiation. Given the potent immuno-regulatory functions of NKT cells, these findings have important implications for the development of novel NKT cell-based therapeutics and vaccines.

Presence of distinct subsets of cytolytic CD8+ T cells in chronic HIV infection

Cytolytic T lymphocytes (CTL) play an important role in the control of HIV infection. The eventual failure to contain HIV-1 infection may arise because of a functional impairment of HIV-specific CTL. We evaluated Gag-specific cytotoxicity in HIV-1-positive Ugandans. Expression of CD107, a marker for cytolytic activity, was present in CD45RA(bright) and CD45RA(dim) CD8(+) T cell populations in HIV-infected individuals. The frequency of Gag-specific CD107(+)CD45RA(bright)CD28(-)CCR7(-) CD8(+) T cells decreased with CD4 cell depletion and correlated with the presence of Gag-specific T helper response. In contrast, the frequency of Gag-specific CD107(+)CD45RA(dim)CD28(-)CCR7(-) CD8(+) T cells within the same individuals has no significant association with viral load or CD4 cell count. The ratio of CD45RA(bright) to CD45RA(dim) CTL correlates significantly with CD4 cell count. This positive association decreases with antiretroviral treatment (ARV), indicating that suppression of viral replication alters the balance of circulating Gag-specific CD8(+) effector T cells. Subsets of cytolytic T cells may have distinct antiviral functions and further characterization of these effector CD8(+) T cells may yield important information on T cell regulation and dysfunction in HIV infection.

Expression of CD103 identifies human regulatory T-cell subsets

BACKGROUND

Analysis of naturally occurring T regulatory CD4+ (nTreg) cells in human diseases is hampered by the lack of specific surface marker. Indeed, the CD25 antigen, which is typically used to identify nTreg cells, is also expressed on activated effector T cells.

OBJECTIVE

We sought to examine whether CD4+ T cells bearing CD103 are suppressor cells, regardless of CD25 coexpression.

METHODS

We first compared freshly isolated tonsillar CD103+ CD25- cells with their CD103- CD25high counterparts for their capacity to suppress T-cell response and their expression of FoxP3 mRNA. Next CD103 was induced on neonatal or adult CD4+ T cells stimulated with allogeneic dendritic cells, and the CD103+ and CD103- fractions were compared as above.

RESULTS

Tonsillar CD4+ CD103+ CD25- T cells displayed comparable suppressive activity and contained similar amounts of FoxP3 mRNA as their CD103- CD25high counterparts. In vitro-generated alloantigen-primed CD103+ cells coexpressed CD25, suppressed T-cell activation, and contained more FoxP3 mRNA than the CD103- CD25+ cells isolated from the same cultures. Finally, neonatal alloreactive cells contained more CD103+ Treg cells than their adult counterparts and, unlike the latter, became hyporesponsive to the priming alloantigens.

CONCLUSIONS

The examination of CD103 and CD25 coexpression allows identification of 3 subsets of human CD4+ nTreg cells, and the detection of CD103 on CD4+ T cells identifies nTreg cells, regardless of CD25 coexpression.

CLINICAL IMPLICATIONS

The greater induction of CD103+ suppressor cells by cord blood should be related to its successful clinical use as an alternative to adult bone marrow transplantation.

Three Memory Subsets of Human CD8+T Cells Differently Expressing Three Cytolytic Effector Molecules

Multicolor flow cytometric analysis for the expression of three effector molecules, i.e., perforin (Per), granzyme A (GraA), and granzyme B (GraB), in human CD8(+) T cells demonstrated that they included five subpopulations, implying the following pathway for the differentiation of CD8(+) T cells: Per(-)GraA(-)GraB(-)-->Per(-)GraA(+)GraB(-)-->Per(low)GraA(+)GraB(-)--> Per(low)GraA(+)GraB(+)-->Per(high)GraA(+)GraB(+). The analysis of the expression of these molecules in the subsets classified by the combination of the expression of CCR7 and CD45RA or by that of CD27, CD28, and CD45RA showed that functional CD8(+) T cell subsets could be partially identified by these phenotypic classifications. However, the functional subsets could be precisely identified by the classification using five cell surface markers or three cell surface markers and three cytolytic molecules. Per(-)GraA(-)GraB(-) and Per(-/low)GraA(+)GraB(-) cells were predominantly found in CCR5(-)CCR7(+) and CCR5(high/low)CCR7(-) subsets, respectively, of CD8(+) T cells expressing the CD27(+)CD28(+)CD45RA(-) phenotype, whereas Per(low)GraA(+)GraB(+) cells were found in the CCR5(low)CCR7(-) subset of those expressing this phenotype and in a part of the CCR5(-/low)CCR7(-) subset of those expressing the CD27(-/low)CD28(-)CD45RA(-/+) phenotype. Ex vivo EBV-specific CD8(+) T cells, which were Per(low/-)GraA(+)GraB(-/+) cells, hardly or very weakly killed the target cells, indicating that these were not effector T cells. These findings suggest that the Per(-)GraA(-)GraB(-), Per(-/low)GraA(+)GraB(-), and Per(low)GraA(+)GraB(+) cells were central memory, early effector memory, and late effector memory T cells, respectively. Per(-/low)GraA(+)GraB(-) cells gained GraB expression after TCR stimulation, indicating that early effector memory T cells could differentiate into late effector and effector T cells. The present study showed the existence of three memory subsets and the pathway for their differentiation.

B7H1-Ig fusion protein activates the CD4+ IFN-gamma receptor+ type 1 T regulatory subset through IFN-gamma-secreting Th1 cells

It has been demonstrated in our previous work that, in the human skin-grafting model, the expression of costimulatory molecule B7H1 (PD-L1) by keratinocytes plays an essential role in inducing local tolerance via activation of IL-10-secreting T cells. This study further analyzes the role of B7H1 in differentiation of type 1 T regulatory (Tr1) cells and explores underlying mechanisms. Mouse fusion protein B7H1-Ig is used, together with immobilized anti-CD3 mAb, to costimulate the purified naive CD4+ T cells. B7H1-Ig-treated CD4+ T cells were found to activate a characteristic Tr1 population possessing a CD4+ CD25- Foxp3- CD45RBlow phenotype. These regulatory T cells strongly inhibited the Th1-dominated MLR by secretion of IL-10 and TGF-beta. Moreover, B7H1-treated Tr1 cells also resulted in suppressed clinical scores and demyelination when adoptively transferred into mice with experimental allergic encephalomyelitis. Furthermore, analysis of the cytokine profile indicated that there were two differential reaction patterns during the B7H1-Ig-induced Tr1 development. These two patterns were characterized by activation of IFN-gammaR+ IL-10R- Th1 and IFN-gammaR+ IL-10R+ Tr1 cells, respectively. Secretion of IFN-gamma by Th1 and the expression of IFN-gammaR on Tr1 were critical for further Tr1 differentiation, as demonstrated by mAb blocking and by analysis in IFN-gamma(-/-) mice. In conclusion, B7H1 is capable of inducing Tr1 differentiation from naive CD4+ T cells by coactivation in an IFN-gamma- or Th1-dependent manner. Our study may shed some light upon the clinical usage of B7H1 as a therapeutic reagent for induction of tolerance.

Pilot study of allogeneic G-CSF-stimulated bone marrow transplantation: harvest, engraftment, and graft-versus-host disease

Peripheral blood progenitor cell (PBPC) harvests mobilized by granulocyte colony-stimulating factor (G-CSF) contain more CD34+ cells and provide more rapid engraftment than do bone marrow (BM) harvests. However, some reports have suggested a higher risk of chronic graft-versus-host disease (GVHD), possibly because such PBPC harvests contain approximately 10 times more T lymphocytes than do BM harvests. Some groups are attempting to combine the faster engraftment of PBPCs with the lower incidence of GVHD observed after BM transplantation by using G-CSF-primed BM conventionally harvested from iliac crests for allogenic BM transplantation. We report the results of a pilot study of 38 allogeneic transplants using G-CSF-stimulated BM from related donors, with a focus on the harvest composition, engraftment, and incidence of acute and chronic GVHDs.

Type 2 Cytotoxic T Lymphocytes Modulate the Activity of Dendritic Cells Toward Type 2 Immune Responses

Activated CD8+ T cells can differentiate into type 1 (Tc1) cells, producing mainly IFN-gamma, and type 2 (Tc2) cells, producing mostly IL-4, IL-5, and IL-10. Tc1 cells are potent CTL involved in the defense against intracellular pathogens and cancer cells. The role of Tc2 cells in the immune response is largely unknown, although their presence in chronic infections, cancer, and autoimmune diseases is associated with disease severity and progression. Here, we show that mouse Tc2 cells modify, through a cell-to-cell contact mechanism, the function of bone marrow-derived dendritic cells (DC). Indeed, Tc2-conditioned DC displayed a reduced expression of MHC class II and costimulatory molecules, produced IL-10 instead of IL-12, and favored the differentiation of both naive CD4+ and CD8+ T cells toward type 2 cells in the absence of added polarizing cytokines. The novel function for Tc2 cells suggests a type 2 loop in which Tc2 cells modify DC function and favor differentiation of naive T cells to type 2 cells. The type 2 loop may at least in part explain the unexpected high frequency of type 2 cells during a chronic exposure to the Ag.

Identification of organ-specific T cell populations by analysis of multiparameter flow cytometry data using DNA-chip analysis software

BACKGROUND

The analysis of cells from multiple experimental groups by multiparameter flow cytometry leads to the generation of complex data sets, for which adequate analysis tools are not commonly available. We report here that software designed for transcriptomics applications can be used in multiparameter flow cytometry.

METHODS

Lymphocytes isolated from nine different mouse organs were stained and subjected to 10-parameter flow cytometry. The resulting data set contained 594 different T cell subsets per organ per mouse and was organized into a so-called flow cytometry array (FCA).

RESULTS

Computation of a hierarchical tree revealed that lymph nodes and spleen were populated by similar T cell subsets, while T cells from peripheral organs displayed a diverse subset composition. Furthermore, organ-specific T cell subsets were identified.

CONCLUSIONS

This new FCA concept in flow cytomics proved to be a valuable tool for the fast and unbiased analysis of complex multiparameter flow cytometry data sets. It can be used for assessing disease progression and therapeutic intervention, and for the association of disease-related biomarkers on the protein level.

Secondary memory CD8+ T cells are more protective but slower to acquire a central-memory phenotype

The formation of memory CD8 T cells is an important goal of vaccination. However, although widespread use of booster immunizations in humans generates secondary and tertiary CD8 T cell memory, experimental data are limited to primary CD8 T cell memory. Here, we show that, compared with primary memory CD8 T cells, secondary memory CD8 T cells exhibit substantially delayed conversion to a central–memory phenotype, as determined by CD62L expression and interleukin (IL)-2 production. This delayed conversion to a central–memory phenotype correlates with reduced basal proliferation and responsiveness to IL-15, although in vitro coculture with a high concentration of IL-15 is capable of inducing proliferation and CD62L upregulation. Functionally, secondary memory CD8 T cells are more protective in vivo on a per cell basis, and this may be explained by sustained lytic ability. Additionally, secondary memory CD8 T cells are more permissive than primary memory CD8 T cells for new T cell priming in lymph nodes, possibly suggesting a mechanism of replacement for memory T cells. Thus, primary and secondary memory CD8 T cells are functionally distinct, and the number of encounters with antigen influences memory CD8 T cell function.

Distinct gene expression in human Vdelta1 and Vdelta2 gammadelta T cells following non-TCR agonist stimulation

The two major human gammadelta T cell subsets, Vdelta1 and Vdelta2, display differences in tissue tropism and agonist responses, but we have little insight into global differences that may exist at the gene expression level. This is due to the small numbers of these cells that can be obtained from healthy donors, which limit comprehensive, comparative gene expression analyses. We established a culture method that expands Vdelta1 and Vdelta2 cells from the same PBL preparation to levels sufficient for sorting and microarray analysis. Although the subsets were expanded identically (anti-TCR mAb, plus IL-15), 392 and 614 genes were identified, which were differentially expressed in the two subsets, from two donors, respectively. Approximately 4500 genes changed in both subsets following PMA/ionomycin treatment; about 50% of these genes were subset-specific. Both subsets responded to a crude LPS preparation, but only 6% of the responsive genes were the same. The differentially expressed genes were consistent with Vdelta2 cells being more inflammatory and Vdelta1 cells having more of a regulatory phenotype. Both subsets expressed transcripts encoding an array of innate and NK cell receptors, supporting the relationship of gammadeltaT cells to the innate immune system. Our results indicate that circulating Vdelta1 and Vdelta2 subsets in humans have considerable inherent differences in gene expression following treatment with the same agonist. The patterns of differentially expressed genes are consistent with unique functional roles for these cells in vivo.

The function of gammadelta T cells in innate immunity

Many researchers believe that gammadelta T lymphocytes belong somewhere 'in-between' the innate and adaptive immune systems. Recent studies strongly emphasize the innate features and functions of these cells, including the use of germline elements of the T cell receptor for ligand recognition, segregation into functionally specialized cell populations in correlation with T cell receptor variable gene or protein expression, interactions with cells of the innate system at many levels and, the latest addition, the ability to present antigen. Thus, at present, much evidence suggests that gammadelta T cells function in an innate manner, although they are arguably the most complex and advanced cellular representatives of the innate immune system.

Characterization of T-cell repertoire in hairy cell leukemia patients before and after recombinant immunotoxin BL22 therapy

We previously reported that hairy cell leukemia (HCL) patients have high percentages of CD56+/CD57+/CD3+ large granular lymphocytes consistent with cytotoxic T-lymphocytes (CTLs), and other investigators have reported skewing of the T-cell repertoire. In previous studies of up to seven HCL patients, many of the 22 established T-cell receptor (TCR) beta variable region (TRBV) families showed mono- or oligoclonal restriction. To determine whether percentages of CTLs are correlated with TRBV clonal excess, we studied 20 HCL patients with flow cytometry, PCR of TCR gamma and TRBV regions, and fractional gel electrophoresis of PCR-amplified TRBV CDR3 domains (CDR3 spectratyping). Increased percentages of CD3+/CD8+/CD57+ CTLs correlated with more mono/oligoclonal and fewer polyclonal TRBV families (r=0.53; P=0.016). Age correlated with number of mono/oligoclonal TRBV families (r=0.51; P=0.022). Time since last purine analog therapy correlated with number of polyclonal TRBV families (r=0.46; P=0.040), but treatment with the anti-CD22 recombinant immunotoxin BL22 was not related to clonal excess. We conclude that abnormalities in the T-cell repertoire in HCL patients may represent deficient immunity, and may be exacerbated by purine analogs. Increased CD3+/CD57+ T-cells may be a useful marker of abnormal TRBV repertoire in HCL patients, and might prove useful in deciding whether patients should receive biologic antibody-based treatment rather than repeated courses of purine analog for relapsed disease.

Lesional T-cell subset in post-kala-azar dermal leishmaniasis

BACKGROUND

The pathogenesis of post-kala-azar dermal leishmaniasis (PKDL) is ill understood. This study was carried out to find the percentage of T-helper and T-suppressor cells in lesional tissue and their probable role in the pathogenesis of PKDL.

METHODS

An immunoperoxidase monoclonal antibody technique was used to characterize and quantify the subsets of T lymphocytes in the infiltrate in 25 patients with PKDL.

RESULTS

The ratio of T-helper to T-suppressor cells was 0.87 in hypopigmented macules and 0.85 in nodule and/or plaque lesions of PKDL.

CONCLUSIONS

In this study, there was a definite preponderance of T-suppressor cells over T-helper cells in both types of skin lesions of PKDL. Further studies should be undertaken on larger numbers of patients to compare T-cell subsets both in skin lesions and the circulation, in order to determine the pathogenesis of PKDL.

Naturally-occurring CD4+CD25+ immunoregulatory T cells: central players in the arena of peripheral tolerance

Self/non-self discrimination is a complex process that involves maintaining tolerance to autoantigens while preserving the potential to generate an effective humoral and cellular immune responses against invading pathogens. In the last decade, there has been a remarkable resurgence in research on suppressor or regulatory T cells. Few areas have captivated the attention of immunologists so vividly and entertained so many passionate debates. Indeed, CD4(+)CD25(+) Treg, which are at the very center of this fascination, have emerged as a dominant T cell population capable of mediating peripheral tolerance to autoantigens, but whose functions have now been extended to regulation of T cell responses directed to foreign antigens. However, a number of fundamental questions concerning the origin, phenotypic nature and mechanism of action of CD4(+)CD25(+) Treg cells remain elusive and misunderstood. We propose the existence of two general subsets of CD4(+)CD25(+) Treg cells, naturally-occurring and induced, that differ in their origin, developmental and activation requirements, and mechanism of action.

Ontogenesis and functional aspects of oxytocin and vasopressin gene expression in the thymus network

Ontogenesis of oxytocin (OT) and vasopressin (VP) gene expression and function were investigated in murine thymus. OT and VP transcripts were detected in the thymus on embryonic days 13 and 15, respectively. Corresponding messenger RNAs were evidenced in thymic epithelial cells by in situ hybridization with a neurophysin probe. From all OT and VP receptors, only OTR was expressed by all T-cell subsets, while V1bR was found in double positive and single positive CD8 cells. In fetal thymic organ cultures, OTR antagonist d[D-Tyr(Et)2, Thr4]OVT increased early apoptosis of CD8 cells, while V1bR antagonist (Sanofi SSR149415) inhibited T-cell differentiation, and favored CD8 T-cell commitment.

B cells CD19+ in patients with B-cell chronic lymphocytic leukaemia and autoimmune haemolytic anaemia

The study presents results of B and T lymphocytes population analysis in patients with chronic lymphocytic leukaemia B cells and autoimmune haemolytic anaemia (CLL-B + AIHA). We evaluated the following groups of patients: (1) with newly recognized CLL-B and co-existent AIHA (untreated), (2) after short-term treatment with corticosteroids, (3) after treatment with chemotherapy and corticosteroids. The control groups were made of patients with CLL-B without AIHA. The populations of lymphocytes and determination of cells immunophenotype were performed by means of flow cytometry. The analysed data were obtained from 25 patients. The untreated patients with CLL-B + AIHA presented significantly more numerous population of neoplastic cells CD19+ CD5+ in comparison with patients without AIHA. The patients with AIHA showed a reduced percentage of B CD19+ CD22+ cells in comparison with those without AIHA. Untreated patients with AIHA or after a short-term corticosteroid treatment showed a higher ratio of the number of CD19+ CD5+ cells to the number of T CD4+ and T CD8+ lymphocytes than CLL-B patients without AIHA. It can be presumed that the differences found may be related to the pathogenesis of the autoimmune haemolysis syndrome in patients with CLL-B.

CD4+CD25+regulatory T cells: I. Phenotype and physiology

The immune system protects us against foreign pathogens. However, if fine discrimination between self and non-self is not carried out properly, immunological attacks against self may be launched leading to autoimmune diseases, estimated to afflict up to 5% of the population. During the last decade it has become increasingly clear that regulatory CD4+CD25+ T cells (Treg cells) play an important role in the maintenance of immunological self-tolerance, and that this cell subset exerts its function by suppressing the proliferation or function of autoreactive T cells. Based on human and murine observations, this review presents a characterization of the phenotype and functions of the Treg cells in vitro and in vivo. An overview of the surface molecules associated with and the cytokines produced by the Treg cells is given and the origin, activation requirements and mode of action of the Treg cells are discussed. Finally, we address the possibility that Treg cells may play a central role in immune homeostasis, regulating not only autoimmune responses, but also immune responses toward foreign antigens.

Relative Proportions of T-Cell Subpopulations and Cytokines That Mediate and Regulate the Adaptive Immune Response in Patients With Aggressive Periodontitis

BACKGROUND

Both the virulence factors of periodontopathic bacteria and the immune response against them have been involved in tissue destruction observed in periodontal disease. Considering the regulatory role of cytokines produced by T cells, the purpose of this study was to compare the CD3+, CD4+, and CD8+ subpopulations of T cells, and to characterize the mRNA of cytokines involved in the adaptive immune response in a group of healthy/gingivitis 1 (HI/G1) individuals and aggressive periodontitis (AgP) patients.

METHODS

The percentages of T-cell subpopulations were analyzed in 10 gingival samples of HI/G1 individuals and 10 gingival samples of AgP patients by immunohistochemistry. The presence of interleukin (IL)-2, interferon (IFN)-gamma, IL-4, IL-5, IL-10, IL- 13, and transforming growth factor (TGF)-beta was measured by reverse transcription polymerase chain reaction (RT-PCR) of mRNA extracted from complete gingival biopsies.

RESULTS

Significant differences were found in CD3+ and CD4+ cell counts between both groups. The parameters were lower in the gingival biopsies from AgP patients while CD8+ counts were similar in both groups. The cytokine mRNA analysis showed constant expression of IL-2 and IFN-gamma in all cases. The mRNA of IL-5 and IL-10 was present in the majority of HI/G1 (N = 10, N = 9, respectively) but was not in the AgP group (N = 2, N = 1). IL-13 and TGF-beta were only detected in HI/G1 (N = 2, N = 3) and IL-4 was not detected in any of the individuals.

CONCLUSIONS

These results indicate that the role of the CD8+ subpopulation in aggressive periodontitis lesions is limited. On the other hand, cytokines IL-2 and IFN-gamma may not be relevant in the progression of aggressive periodontitis.

Identification of a novel natural regulatory CD8 T-cell subset and analysis of its mechanism of regulation

The immune system contains natural regulatory T cells that control the magnitude of the immune response during physiologic and pathologic conditions. Although this suppressive function was historically attributed to CD8 T cells, most recent reports have focused on natural regulatory CD4 T cells. In the present study, we describe a new subset of natural CD8 regulatory T cells in normal healthy animals. This subset expresses low levels of CD45RC at its surface (CD45RC(low)); produces mainly interleukin-4 (IL-4), IL-10, and IL-13 cytokines upon in vitro stimulation; expresses Foxp3 and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4); and is not cytotoxic against allogeneic targets. This subset suppresses the proliferation and differentiation of autologous CD4 T cells into type-1 cytokines producing T cells after stimulation with allogeneic accessory cells. We also provide evidence that this regulatory subset mediates its suppression by cell-to-cell contact and not through secretion of suppressive cytokines. Finally, the regulatory activity of CD8 CD45RC(low) cells is also demonstrated in vivo in a rat model of CD4-dependent graft-versus-host disease. Collectively, these data demonstrate for the first time that freshly isolated rat CD8 CD45RC(low) T cells contain T cells with regulatory properties, a result that enlarges the general picture of T-cell-mediated regulation.

Macrophage participation in influenza-induced sleep enhancement in C57BL/6J mice

Mice develop changes in sleep during the nonspecific immune response that occurs during the initial few days after inoculation with influenza virus. T lymphocytes, neutrophils, macrophages, and natural killer (NK) cells all participate in the early host response to influenza infection. All of these cell types are potential sources of endogenous substances that modulate sleep, but the contributory role of each cell type to the alteration of somnolence during infection has not been determined. To investigate which cell types contribute to the sleep enhancement that develops during influenza infection in mice, the sleep patterns of C57BL/6J mice with perturbations of particular facets of host immune response capabilities were assessed before and after influenza infection. Targeted mutation of the gene Ccl3 (macrophage inflammatory protein 1 alpha) prevented development of the dark phase sleep enhancement that is characteristic of C57BL/6J mice after influenza infection. Other experimental treatments that impair macrophage or monocyte function also produced significant (administration of pentoxifylline or CNI-1493) or marginally significant (deletion of the interferon-gamma gene or intranasal administration of carrageenan) changes in influenza-induced sleep enhancement in C57BL/6J mice. In contrast, functional impairments of NK cells, neutrophils, and T lymphocytes did not significantly influence sleep responses. These data therefore support a contributory role for macrophages, but not for NK cells, neutrophils, and T lymphocytes, in eliciting the sleep response typical of influenza-infected C57BL/6J mice.

Human CD25+ regulatory T cells: two subsets defined by the integrins alpha 4 beta 7 or alpha 4 beta 1 confer distinct suppressive properties upon CD4+ T helper cells

Down-regulation of autoreactive T cell responses in vivo includes cell-contact-dependent as well as contact-independent mechanisms. Infectious tolerance is a contact-dependent mechanism used by naturally occurring CD25(+) T regulatory cells (Tregs) to confer suppressive activity upon conventional CD4(+) T cells thereby generating secondary T helper suppressor cells(Th(sup)), which inhibit T cell activation via soluble mediators. Here, we describe two distinct subsets of human Tregs, characterized by expression of either the alpha(4)beta(7) integrin or the alpha(4)beta(1) integrin. Upon activation, both subsets show an enhanced expression of FoxP3, recently described as a key transcription factor of murine Tregs. In addition, both are able to convey suppressive capacity to conventional CD4(+) T cells. However, the properties of Treg subsets are rather distinct: alpha(4)beta(7) (+)Tregs induce IL-10-producing Th(sup) (Tr1-like), whereas alpha(4)beta(1) (+) Tregs induce TGF-beta-producing Th(sup) (Th3-like). Our findings reconcile conflicting results by clearly demonstrating that suppression through naturally occurring CD25(+) Tregs is primary cell-contact-dependent but is subsequently followed by cell-contact-independent T cell inhibition mediated by second-generation Tr1- and Th3-like Th(sup) via the soluble factors IL-10 and TGF-beta.