[Circulating populations of CD4+ CD25+ CD127- regulatory t lymphocytes in peripheral blood of allergic asthmatic children]

OBJECTIVE

To carry out a preliminary analysis on the Treg lymphocyte counts present in the peripheral blood of allergic asthmatic children from the city of Cartagena, Colombia, compared to healthy controls.

METHODS

We compared cytometry counts of ten asthmatic patients (age 7-16 years) and seven healthy controls (6-12 years), recruited in the city of Cartagena. Peripheral blood samples were stained using Cytek's 14-color cFluor Immunoprofiling kit (Cytek® cFluor® Immunoprofiling Kit 14 Color RUO kit), and analyzed on a Northern Lights™ spectral cytometer (Cytek® Biosciences, Fremont, CA, USA), to read 50.000 events per sample. The data obtained were analyzed in SpectroFlo® and FlowJo. The study was approved by the ethics committee of the University of Cartagena (SGR, Grant BPIN2020000100405).

RESULTS

The frequency of CD3+, CD4+, CD25+, CD127- Tregs was 11% of all CD4+ T cells, with a range of minimum 8,1% and maximum 17,7%. There was no significant difference in the proportion of Tregs between allergic asthmatic patients and healthy controls (P = 0,2).

CONCLUSIONS

With this preliminary sample size, no significant differences were found in the Treg lymphocyte population between allergic asthmatic patients and healthy controls. The 14-color multiplexed panel is a useful tool not only to count CD3+ and CD4+ populations, but also to obtain the percentage of regulatory T cells using cell surface markers.

Some Aspects of CD8+ T-Cell Exhaustion Are Associated With Altered T-Cell Mitochondrial Features and ROS Content in HIV Infection

BACKGROUND

Reversing or preventing T-cell exhaustion is an important treatment goal in the context of HIV disease; however, the mechanisms that regulate HIV-specific CD8 T-cell exhaustion are incompletely understood. Since mitochondrial mass (MM), mitochondrial membrane potential (MMP), and cellular reactive oxygen species (ROS) content are altered in exhausted CD8 T cells in other settings, we hypothesized that similar lesions may arise in HIV infection.

METHODS

We sampled cryopreserved peripheral blood mononuclear cells from HIV-uninfected (n = 10) and HIV-infected participants with varying levels and mechanisms of viral control: viremic (VL > 2000 copies/mL; n = 8) or aviremic (VL < 40 copies/mL) due to antiretroviral therapy (n = 11) or natural control (n = 9). We characterized the MM, MMP, and ROS content of bulk CD8 T cells and MHC class I tetramer+ HIV-specific CD8 T cells by flow cytometry.

RESULTS

We observed higher MM, MMP, and ROS content across bulk effector-memory CD8 T-cell subsets in HIV-infected compared with HIV-uninfected participants. Among HIV-specific CD8 T cells, these features did not vary by the extent or mechanism of viral control but were significantly altered in cells displaying characteristics associated with exhaustion (eg, high PD-1 expression, low CD127 expression, and impaired proliferative capacity).

CONCLUSIONS

While we did not find that control of HIV replication in vivo correlates with the CD8 T-cell MM, MMP, or ROS content, we did find that some features of CD8 T-cell exhaustion are associated with alterations in mitochondrial state. Our findings support further studies to probe the relationship between mitochondrial dynamics and CD8 T-cell functionality in HIV infection.

Lack of correlation between Treg quantification assays in inflammatory bowel disease patients

AIM: To compare the number of regulatory T-cells (Tregs) measured by flow cytometry with those obtained using a real-time quantitative PCR (qPCR) method in patients suffering from inflammatory bowel disease (IBD).

METHODS: Tregs percentages obtained by both flow cytometry and qPCR methods in 35 adult IBD patients, 18 out of them with Crohn´s disease (CD) and 17 with ulcerative colitis (UC) were compared to each other as well as to scores on two IBD activity questionnaires using the Harvey Bradshaw Index (HBI) for CD patients and the Simple Colitis Clinical Activity Index (SCCAI) for UC patients. The Treg percentages by flow cytometry were defined as CD4⁺CD25^highCD127^lowFOXP3⁺ cells in peripheral blood mononuclear cells, whereas the Treg percentages by qPCR method were determined as FOXP3 promoter demethylation in genomic DNA.

RESULTS: We found an average of 1.56% ± 0.78% Tregs by using flow cytometry, compared to 1.07% ± 0.53% Tregs by using qPCR in adult IBD patients. There were no significant correlations between either the percentages of Tregs measured by flow cytometry or qPCR and the HBI or SCCAI questionnaire scores in CD or UC patients, respectively. In addition, there was no correlation between Treg percentages measured by qPCR and those measured by flow cytometry (r = -0.06, P = 0.73; Spearman Rho). These data suggest that, either Treg-related immune function or the clinical scores in these IBD patients did not accurately reflect actual disease activity. Until the cause(s) for these differences are more clearly defined, the results suggest caution in interpreting studies of Tregs in various inflammatory disorders.

CONCLUSION: The two methods did not produce equivalent measures of the percentage of total Tregs in the IBD patients studied which is consistent with the conclusion that Tregs subtypes are not equally detected by these two assays.

[Changes and the implications of CD4(+);CD25(+);CD127(low); regulatory T cells in drug addicts during natural drug withdrawal]

OBJECTIVE

To study the changes of CD4(+);CD25(+);CD127(low); regulatory T cells (Tregs) and transforming growth factor beta 1 (TGF-β1) mRNA in peripheral blood mononuclear cells (PBMCs) in drug addicts during natural drug withdrawal, and explore the effects of addictive drugs on their Tregs.

METHODS

Peripheral blood was collected from 40 drug addicts with 6-month natural withdrawal, 40 cases with 18-month natural withdrawal and 30 healthy controls. Then the Tregs were counted by flow cytometry and TGF-β1 mRNA expression in PBMCs was detected by RT-PCR.

RESULTS

Compared with the controls, Tregs and TGF-β1 mRNA expression in PBMCs increased significantly in the group with one 18-month natural withdrawal, but no significant difference was found in the group with 6-month natural withdrawal.

CONCLUSION

Addictive drugs have a long-term effect on the Tregs in drug addicts, and the abnormal Tregs may result in the immune dysfunction in drug addicts.

Human mesenchymal stem cells elevate CD4+CD25+CD127low/- regulatory T cells of asthmatic patients via heme oxygenase-1

Up-regulation of CD4+CD25+CD127low/- regulatory T cells (Tregs) is a new target in the treatment of asthma. Human bone marrow mesenchymal stem cells can up-regulate CD4+CD25+CD127low/- regulatory T cells in vitro, meanwhile, heme oxygenase-1 (HO-1) plays an important role in the development and maintenance of CD4+CD25+ regulatory T cells. However the mechanism has not yet been adequately understood. Hence, we wondered what effect of Heme Oxygenase-1 made on regulation of CD4+CD25+CD127low/- regulatory T cells mediated by mesenchymal stem cells. Peripheral blood mononuclear cells isolated from asthmatic patients and healthy controls were co-cultured with human bone marrow mesenchymal stem cells which were pretreated with Hemin (the revulsive of Heme Oxygenase-1), Protoporphyrin Ⅸ zinc (the inhibitor of Heme Oxygenase-1) and saline. The expression of Heme Oxygenase-1 in MSCs was enhanced by Hemin and inhibited by Protoporphyrin  zinc in vitro. Overexpression of Heme Oxygenase-1 elevated the proportion of CD4+CD25+CD127low/- regulatory T cells in CD4+ T cells, meanwhile, inhibition of Heme Oxygenase-1 decreased the proportion of CD4+CD25+CD127low/- regulatory T cells in CD4+ T cells as compared with mesenchymal stem cells alone. Taken together, these data demonstrated that Heme Oxygenase-1 contributed to the up-regulation of CD4+CD25+CD127low/- regulatory T cells mediated by mesenchymal stem cells in asthma. 

[Analysis of CD4(+)CD25(+)CD127(low/-) Treg cells in mice]

The quantitative identification and enrichment of viable regulatory T cells (Treg) requires reliable surface markers that are selectively expressed on Treg. Foxp3 is the accepted marker of natural Treg, but it cannot be used to isolate cells for functional studies. CD127 is a new surface marker expressed in Treg cells. In this study, two populations of Treg, including CD4(+)CD25(+)CD127(low/-) and CD4(+)CD25(+)Foxp3(+)T cells, and profiles of the Foxp3 expression in CD4(+)CD25(+)CD127(low/-) cells were compared to evaluate which population is better. The peripheral blood cells were collected and spleen suspension of BALB/C mice were prepared, and using triple staining CD4, CD25, CD127 and CD4, CD25, Foxp3. The profiles of Treg, including CD4(+)CD25(+)CD127(low/-) and CD4(+)CD25(+)Foxp3(+) were detected by flow cytometry. The quadruple staining CD4, CD25, Foxp3 and CD127 were used to determine the CD127 expression in CD4(+)CD25(+)Foxp3(+) cells. The results showed that on T cell subset the median expression levels of CD4(+), CD4(+)CD25(+) were 39.02%, 5.35% in peripheral blood and 23.49%, 3.86% in spleen. On CD4(+) T cell subset, the median expression level of CD4(+)CD25(+)CD127(low/-) and CD4(+)CD25(+)Foxp3(+)T cells were 7.13%, 3.97% in peripheral blood and 12.8%, 8.23% in spleen. The ratio of CD4(+)CD25(+)CD127(low/-) T cells was higher than that of CD4(+)CD25(+)Foxp3(+) cells in both peripheral blood and spleen cells (P < 0.01). The CD4(+)CD25(+)CD127(low/-) cells highly expressed Foxp3, while the CD4(+)CD25(+)Foxp3(+)T cells lowly expressed CD127. It is concluded that compared with the CD4(+)CD25(+)Foxp3(+) populations, CD4(+)CD25(+)CD127(low/-) T cells better fit the definition of naturally occurring regulatory T cells in peripheral blood cells and spleen of BALB/C mice. CD127(low/-) is a characteristic marker on surface of CD4(+)CD25(+) Treg cells, and has been confirmed to be more specific marker for quantitatively sorting Treg cells.

[The subpopulation CD4(+); CD25(+); Foxp3(+);/CD127(low/-); regulatory T cells in peripheral blood of HIV-infected patients correlated with disease progression]

AIM

To explore the subpopulation of CD4(+); CD25(+); Foxp3(+); regulatory T cells (Treg), CD4(+); CD25(+); CD127(low/-); Treg in peripheral blood of HIV-infected patients and study its correlation with other immune indicators.

METHODS

We enrolled 68 cases of HIV/AIDS patients without anti-HIV treatment [29 cases of long-term non-progressive (LTNP) group, 27 cases of typical progressive HIV infection group and 12 cases of AIDS group] and 20 healthy individuals as a control group. Blood samples of these cases were analyzed by flow cytometry after immunofluorescent staining to determine the levels of CD4(+); T cells, CD8(+); T cells, NK cells and CD4(+); CD25(+); Foxp3(+);/CD127(low/-); Treg.

RESULTS

Except CD8(+); T cells, the levels of CD4(+); T, NK cells and CD4(+);/CD8(+); in peripheral blood of HIV/AIDS patients were significantly lower than those in the control group (P<0.05); With the progression of disease, the percentage and absolute count of CD4(+);T cells, the absolute counts of CD8(+);T cells and NK cells, and CD4(+);/CD8(+); T cell ratio in the LTNP group, HIV group and AIDS group decreased gradually, while the percentage of CD8(+);T cells increased gradually. Our multiple comparison analysis revealed that the percentages of CD4(+); CD25(+); Foxp3(+); Treg and CD4(+); CD25(+); CD127(low/-); Treg in CD4(+); T cells were significantly different among groups (P<0.05). With the progression of disease, the percentages of CD4(+); CD25(+); Foxp3(+); Treg and CD4(+); CD25(+); CD127(low/-); Treg increased gradually; in addition, the difference in the absolute count of CD4(+); CD25(+); Foxp3(+);/CD127(low/-); Treg was not statistically significant between LTNP group and healthy control group(P>0.05), so was between HIV and AIDS groups (P>0.05); no significant difference was found in every other two groups (P<0.05); the absolute count of CD4(+); CD25(+); Foxp3(+);/CD127(low/-); Treg decreased gradually.

CONCLUSION

CD4(+); CD25(+); Foxp3(+);/CD127(low/-); Treg may play a role in the immunopathogenesis of persistent HIV infection.

Regulatory T cells in the pathogenesis and healing of chronic human dermal leishmaniasis caused by Leishmania (Viannia) species

BACKGROUND

The inflammatory response is prominent in the pathogenesis of dermal leishmaniasis. We hypothesized that regulatory T cells (Tregs) may be diminished in chronic dermal leishmaniasis (CDL) and contribute to healing during treatment.

METHODOLOGY/PRINCIPAL FINDINGS

The frequency and functional capacity of Tregs were evaluated at diagnosis and following treatment of CDL patients having lesions of ≥6 months duration and asymptomatically infected residents of endemic foci. The frequency of CD4(+)CD25(hi) cells expressing Foxp3 or GITR or lacking expression of CD127 in peripheral blood was determined by flow cytometry. The capacity of CD4(+)CD25(+) cells to inhibit Leishmania-specific responses was determined by co-culture with effector CD4(+)CD25(-) cells. The expression of FOXP3, IFNG, IL10 and IDO was determined in lesion and leishmanin skin test site biopsies by qRT-PCR. Although CDL patients presented higher frequency of CD4(+)CD25(hi)Foxp3(+) cells in peripheral blood and higher expression of FOXP3 at leishmanin skin test sites, their CD4(+)CD25(+) cells were significantly less capable of suppressing antigen specific-IFN-γ secretion by effector cells compared with asymptomatically infected individuals. At the end of treatment, both the frequency of CD4(+)CD25(hi)CD127(-) cells and their capacity to inhibit proliferation and IFN-γ secretion increased and coincided with healing of cutaneous lesions. IDO was downregulated during healing of lesions and its expression was positively correlated with IFNG but not FOXP3.

CONCLUSIONS/SIGNIFICANCE

The disparity between CD25(hi)Foxp3(+) CD4 T cell frequency in peripheral blood, Foxp3 expression at the site of cutaneous responses to leishmanin, and suppressive capacity provides evidence of impaired Treg function in the pathogenesis of CDL. Moreover, the concurrence of increased Leishmania-specific suppressive capacity with induction of a CD25(hi)CD127(-) subset of CD4 T cells during healing supports the participation of Tregs in the resolution of chronic dermal lesions. Treg subsets may therefore be relevant in designing immunotherapeutic strategies for recalcitrant dermal leishmaniasis caused by Leishmania (Viannia) species.

Lymphoid progenitors in normal mouse lymph nodes develop into NK cells and T cells in vitro and in vivo

We have identified a population of normal mouse LN cells, termed LN lymphoid progenitor (LNLP), resembling common lymphoid progenitor (CLP) in the bone marrow. LNLPs lack lineage markers and express CD127, low levels of CD117 (c-Kit), and Sca-1, but lack fms-related tyrosine kinase 3. They efficiently differentiate in vitro into natural killer (NK) cells and T cells, but not mature B cells. LNLPs injected into nonirradiated lymphopenic mice that have no LN develop into mostly splenic T cells with low numbers of NK cells and B cells. When injected into irradiated mice, they generate NK cells and T cells, but not B cells, in the LN. By contrast, bone marrow CLPs develop into mostly B cells with very small numbers of T and NK cells in recipients' spleen and LN. LNLPs have NK and T-cell potentials, but little B-cell potential, and they can develop into NK cells within the LN of normal mice, but their contribution to the T-cell lineage is unknown.

Increased frequency of regulatory T cells and T lymphocyte activation in persons with previously treated extrapulmonary tuberculosis

Extrapulmonary tuberculosis may be due to underlying immune compromise. Immunosuppressive regulatory T cells (Treg cells), and CD4(+) T lymphocytes in general, are important in the host immune response to Mycobacterium tuberculosis. We evaluated T lymphocytes from patients after recovery from extrapulmonary tuberculosis, which may reflect conditions before M. tuberculosis infection. A case-control study was conducted among HIV-uninfected adults with previously treated extrapulmonary tuberculosis and 3 sets of controls: (i) subjects with previously treated pulmonary tuberculosis, (ii) close tuberculosis contacts with M. tuberculosis infection, and (iii) close tuberculosis contacts with no infection. Monocyte-depleted peripheral blood mononuclear cells (PBMC-M) were stained for CD4(+) CD25(hi) CD127(low) FoxP3(+) cell (Treg cell) and T lymphocyte activation. Both characteristics were compared as continuous variables between groups with the Kruskal-Wallis test. There were 7 extrapulmonary tuberculosis cases, 18 pulmonary tuberculosis controls, 17 controls with M. tuberculosis infection, and 18 controls without M. tuberculosis infection. The median Treg cell proportion was highest among persons with previous extrapulmonary tuberculosis (1.23%) compared to subjects with pulmonary tuberculosis (0.56%), latent M. tuberculosis infection (0.14%), or no M. tuberculosis infection (0.20%) (P = 0.001). The median proportion of CD4(+) T lymphocytes that expressed the activation markers HLA-DR and CD38 was highest for CD4(+) T lymphocytes from persons with previous extrapulmonary tuberculosis (0.79%) compared to subjects with pulmonary tuberculosis (0.44%), latent M. tuberculosis infection (0.14%), or no M. tuberculosis infection (0.32%) (P = 0.005). Compared with controls, persons with previously treated extrapulmonary tuberculosis had the highest Treg cell frequency, but also the highest levels of CD4(+) T lymphocyte activation. Immune dysregulation may be a feature of individuals at risk for extrapulmonary tuberculosis.

[Levels of regulatory T cells in peripheral blood of children with idiopathic thrombocytopenic purpura]

OBJECTIVE

To study the levels of CD4+CD25+CD127- and CD3+CD4-CD8- regulatory T (Treg) cells in peripheral blood of children with idiopathic thrombocytopenic purpura (ITP).

METHODS

The flow cytometry was used to detect the expression of CD4+CD25+CD127- and CD3+CD4-CD8- Treg cells in peripheral blood of 33 children with ITP and 21 healthy children.

RESULTS

The expression levels of CD4+CD25+CD127-［(2.7±1.7)% vs (4.8±1.6)%; P<0.01］and CD3+CD4-CD8-［(5.2±3.1)% vs (8.1±3.5)%; P<0.01］Treg cells in children with ITP were significantly lower than in the controls.

CONCLUSIONS

The expression levels of CD4+CD25+CD127- and CD3+CD4-CD8- Treg cells decrease in children with ITP, suggesting that CD4+CD25+CD127- and CD3+CD4-CD8- Treg cells might play a role in the pathogenesis of ITP.

[Detection and significance of CD4+ CD25int/high CD127low regulatory T cells in pediatric aplastic anemia]

OBJECTIVE

To study the expression of CD4+ CD25int/high CD127low regulatory T cells in peripheral blood (PB) and its relation to the quantity of Hb, WBC and platelet (Plt) in children with aplastic anemia (AA).

METHODS

Expression of CD4+ CD25int/high CD127low in PB was detected by flow cytometry in 22 children with AA before and after treatment and in 15 healthy controls. The relationships between CD4+CD25highCD127low and the quantity of Hb, WBC and Plt were evaluated.

RESULTS

Compared to controls, the percentages of CD4+ CD25+/CD4+, CD4+CD25high/CD4+, CD4+ CD25+ CD127low/CD4+ and CD4+CD25highCD127low/CD4+ in PB of AA patients decreased markedly at the active phase (P﹤0.05). By the recovery phase, the percentages of CD4+CD25+/CD4+, CD4+CD25high/CD4+, CD4+ CD25+ CD127low/CD4+ and CD4+CD25highCD127low/CD4+ increased significantly to the levels similar to the controls. There were significant positive relationships between the expression of CD4+CD25highCD127low cells and the quantity of Hb, WBC and Plt (r=0.499, 0.526, 0.540 respectively; P﹤0.05).

CONCLUSIONS

The decrease of the percentage of CD4+CD25int/highCD127low regulatory T cells might be associated with the development of pediatric AA. The CD4+CD25int/highCD127low regulatory T cells can serve as a marker for the evaluation of disease severity as well as a target of further study on immune treatment of AA.

Distributional characteristics of CD25 and CD127 on CD4+ T cell subsets in chronic HCV infection

Attenuated CD4+ T-cell-mediated immune responses are involved in persistence of HCV infection, but the mechanism remains undefined. In this study, the proportions of CD4+ T cell subsets, naïve, central memory, effector memory and effector cells, along with CD25 (IL-2R alpha) and CD127 (IL-7R alpha) expression on different CD4+ T cell subsets, were measured by polychromatic flow cytometry in 24 chronic HCV-infected individuals and 21 healthy controls. A significant decrease in naïve CD4+ T cells and an increase of central memory and effector memory CD4+ T cells were found in HCV-infected patients compared with healthy controls. HCV-infected patients showed a lower level of CD127 expression in all CD4+ T cells subsets, especially in central memory and effector CD4+ T cells. In terms of total CD4+ T cells, an increase in CD25+ regular T cells (CD4+ CD25+ CD127lo) was found in HCV-infected patients. Interestingly, naïve CD4+ T cells showed increased CD25 expression, while effector memory and effector CD4+ T cells had lower CD25 expression. These data indicated that variations in different fractions of CD4+ T cells, including the phenotypic profile and expression level of CD25 and CD127, may be associated with low efficiency of immune response in chronic HCV infection. These results will strengthen the understanding of pathogenesis and dysfunction of CD4+ T cell immunity during long-term HCV persistence.

Vitamin D supplementation and regulatory T cells in apparently healthy subjects: vitamin D treatment for autoimmune diseases?

BACKGROUND

Epidemiological data show significant associations of vitamin D deficiency and autoimmune diseases. Vitamin D may prevent autoimmunity by stimulating naturally occurring regulatory T cells.

OBJECTIVES

To elucidate whether vitamin D supplementation increases Tregs frequency (%Tregs) within circulating CD4+ T cells.

METHODS

We performed an uncontrolled vitamin D supplementation trial among 50 apparently healthy subjects including supplementation of 140,000 IU at baseline and after 4 weeks (visit 1). The final follow-up visit was performed 8 weeks after the baseline examination (visit 2). Blood was drawn at each study visit to determine 25-hydroxyvitamin D levels and %Tregs. Tregs were characterized as CD4+CD25++ T cells with expression of the transcription factor forkhead box P3 and low or absent expression of CD127.

RESULTS

Forty-six study participants (65% females, mean age +/- SD 31 +/- 8 years) completed the trial. 25(OH)D levels increased from 23.9 +/- 12.9 ng/ml at baseline to 45.9 +/- 14.0 ng/ml at visit 1 and 58.0 +/- 15.1 ng/ml at visit 2. %Tregs at baseline were 4.8 +/- 1.4. Compared to baseline levels we noticed a significant increase of %Tregs at study visit 1 (5.9 +/- 1.7, P < 0.001) and 2 (5.6 +/- 1.6, P < 0.001).

CONCLUSIONS

Vitamin D supplementation was associated with significantly increased %Tregs in apparently healthy individuals. This immunomodulatory effect of vitamin D might underlie the associations of vitamin D deficiency and autoimmune diseases. Hence, our finding provides a rationale for further studies to investigate vitamin D effects on autoimmunological processes.

Distinct profiles of cytotoxic granules in memory CD8 T cells correlate with function, differentiation stage, and antigen exposure

Cytotoxic CD8 T cells exert their antiviral and antitumor activity primarily through the secretion of cytotoxic granules. Degranulation activity and cytotoxic granules (perforin plus granzymes) generally define CD8 T cells with cytotoxic function. In this study, we have investigated the expression of granzyme K (GrmK) in comparison to that of GrmA, GrmB, and perforin. The expression of the cytotoxic granules was assessed in virus-specific CD8 T cells specific to influenza virus, Epstein-Barr virus (EBV), cytomegalovirus (CMV), or human immunodeficiency virus type 1 (HIV-1). We observed a dichotomy between GrmK and perforin expression in virus-specific CD8 T cells. The profile in influenza virus-specific CD8 T cells was perforin(-) GrmB(-) GrmA(+/-) GrmK(+); in CMV-specific cells, it was perforin(+) GrmB(+) GrmA(+) GrmK(-/+); and in EBV- and HIV-1-specific cells, it was perforin(-/+) GrmB(+) GrmA(+) GrmK(+). On the basis of the delineation of memory and effector CD8 T cells with CD45RA and CD127, the GrmK(+) profile was associated with early-stage memory CD8 T-cell differentiation, the perforin(+) GrmB(+) GrmA(+) profile with advanced-stage differentiation, and the GrmB(+) GrmA(+) Grmk(+) profile with intermediate-stage differentiation. Furthermore, perforin and GrmB but not GrmA and GrmK correlated with cytotoxic activity. Finally, changes in antigen exposure in vitro and in vivo during primary HIV-1 infection and vaccination modulated cytotoxic granule profiles. These results advance our understanding of the relationship between distinct profiles of cytotoxic granules in memory CD8 T cells and function, differentiation stage, and antigen exposure.

Interleukin-7 enhances proliferation responses to T-cell receptor stimulation in naïve CD4+ T cells from human immunodeficiency virus-infected persons

Proliferation responses of naïve CD4(+) T cells to T-cell receptor and interleukin-7 (IL-7) stimulation were evaluated by using cells from human immunodeficiency virus-positive (HIV(+)) donors. IL-7 enhanced responses to T-cell receptor stimulation, and the magnitude of this enhancement was similar in cells from healthy controls and from HIV(+) subjects. The overall response to T-cell receptor stimulation alone or in combination with IL-7, however, was diminished among viremic HIV(+) donors and occurred independent of antigen-presenting cells. Frequencies of CD127(+) cells were related to the magnitudes of proliferation enhancement that were mediated by IL-7. Thus, IL-7 enhances but does not fully restore the function of naïve CD4(+) T cells from HIV-infected persons.

In vitro expansion of CD4+CD25highFOXP3+CD127low/− regulatory T cells from peripheral blood lymphocytes of healthy Mycobacterium tuberculosis-infected humans

CD4+CD25highFOXP3+ regulatory T (Treg) cells have recently been found at elevated levels in the peripheral blood of tuberculosis patients, compared to Mycobacterium tuberculosis latently infected (LTBI) healthy individuals and non-infected controls. Here, we show that CD4+CD25highFOXP3+ T lymphocytes can be expanded in vitro from peripheral blood mononuclear cells (PBMC) of LTBI individuals, but not of uninfected controls by incubating them with BCG in the presence of TGF-beta. These expanded cells from the PBMC of LTBI subjects expressed CTLA-4, GITR and OX-40, but were CD127low/- and have therefore the phenotype of Treg cells. In addition, they inhibited in a dose-dependant manner the proliferation of freshly isolated mononuclear cells in response to polyclonal stimulation, indicating that they are functional Treg lymphocytes. In contrast, incubation of the PBMC with BCG alone preferentially induced activated CD4+ T cells, expressing CD25 and/or CD69 and secreting IFN-gamma. These results show that CD4+CD25highFOXP3+ Treg cells can be expanded or induced in the peripheral blood of LTBI individuals in conditions known to predispose to progression towards active tuberculosis and may therefore play an important role in the pathogenesis of the disease.

CD4dimCD25bright Treg cell frequencies above a standardized gating threshold are similar in asthmatics and controls

BACKGROUND

Thymus selected CD4(+)CD25(bright) natural regulatory Treg cells expressing FOXP3 may contribute to control of immune responses. No unique markers have been available to identify and characterize Treg. We present a gating strategy that allows enumeration of Treg on the basis of CD4 and CD25 and investigate whether asthmatics have fewer Treg than controls.

METHODS

Asthmatics and controls were selected from responses to a mailed questionnaire. CD25, CD4, HLA DR, and appropriate isotypes were recorded by flow cytometry.

RESULTS

The CD4 T cells expressing most CD25 are a separate population expressing FOXP3 and lower levels of CD4 and CD127. On a CD4 CD25 dot-plot, the CD4 MFI of Treg for 152 participants was calculated to be 0.83 +/- 0.043*MFI of CD25(bright) T-cells. CD4(dim)CD25(bright) T cells in a rectangular gate with a CD4 MFI </= 0.9 (0.83 + [2*0.043])*MFI of CD25(+) T cells were enumerated and shown to be similar for controls (median 8.34%) and asthmatics (median 10.1%). HLA DR expression on Treg correlated with CD25 expression.

CONCLUSIONS

A standardized two color gating method defines Treg. It may be applied in most clinical scenarios and is useful for sorting viable Treg. Asthmatics and controls have similar numbers of Treg.

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.

Subject classification obtained by cluster analysis and principal component analysis applied to flow cytometric data

BACKGROUND

Polychromatic flow cytometry (PFC) allows the simultaneous determination of multiple antigens in the same cell, resulting in the generation of a high number of subsets. As a consequence, data analysis is the main difficulty with this technology. Here we show the use of cluster analysis (CA) and principal component analyses (PCA) to simplify multicolor data visualization and to allow subjects' classification.

METHODS

By eight-colour cytofluorimetric analysis, we investigated the T cell compartment in donors of different age (young, middle-aged, and centenarians). T cell subsets were identified by combining positive and negative expression of antigens. The resulting data set was organized into a matrix and subjected to CA and PCA.

RESULTS

CA clustered people of different ages on the basis of cytofluorimetric profile. PCA of the cellular subsets identified centenarians within a different cluster from young donors, while middle-aged donors were scattered between these groups. These approaches identified T cell phenotypes that changed with increasing age. In young donors, memory T cell subsets tended to be CD127+ and CD95- whereas CD127-, CD95+ phenotypes were found at higher frequencies in people with advanced age.

CONCLUSIONS

Our data suggest the use of bioinformatic approaches to analyze large data-sets generated by PFC and to obtain the rapid identification of key populations that best characterize a group of subjects.

Cutting edge: Antigen is not required for the activation and maintenance of virus-specific memory CD8+ T cells in the lung airways

Respiratory virus infections establish a population of memory CD8(+) T cells in the lung airways that persist for months after infection. However, the relationship between Ag-specific memory T cells in the lung airways and the systemic memory T cell pool is not well understood. The majority of lung airway memory T cells express a highly activated phenotype (CD69(+)/CD127(-)), suggesting that recent Ag stimulation is required to drive T cell activation and recruitment to the lung airways. In this study, we demonstrate that the lung airway environment itself in the absence of cognate Ag alters the expression of acute activation markers such as CD69 and CD127 on memory CD8(+) T cells. Furthermore, the steady-state recruitment of virus-specific memory CD8(+) T cells to the lung airways from the circulation can occur without recent Ag stimulation. These findings alter the current perceptions concerning the contribution of Ag to the maintenance of peripheral T cell memory.

The perivascular space as a path of hematopoietic progenitor cells and mature T cells between the blood circulation and the thymic parenchyma

It is known that selected populations of lymphoid cells migrate into and from the adult thymus through blood vessels at the cortico-medullary junction and in the medulla. Here, we show that in the perivascular spaces (PVS) of mice surrounding large blood vessels, CD117-positive hematopoietic progenitor cells, CD4 single-positive (SP) and CD8SP T cells are located. However, developing thymocytes, CD25-positive cells and CD4 and CD8 double-positive cells, are not detectable in the PVS. After intravenous (i.v.) injection of CD117-positive bone marrow (BM) cells from C57BL/6 mice into non-irradiated RAG2 mutant mice i.v., donor-derived cells first preferentially migrate into the PVS within 30 min, and then the number of donor-derived cells in the thymic parenchyma increases. Likewise, newly developed mature T cells in the thymic parenchyma of RAG2 mutant mice transferred with wild-type BM cells migrate to the PVS, before leaving the thymus to the circulation. Accumulation of mature T cells was observed after treatment with sphingosine-1 phosphate receptor agonist FTY720 not only in the medulla but also in the thymic PVS. These results suggest that the PVS is a transit pathway for progenitor cells to immigrate into the thymus and for mature T cells to emigrate from the thymus.