IL-2 production correlates with effector cell differentiation in HIV-specific CD8+ T cells

BACKGROUND: Diminished IL-2 production and lack of effector differentiation have been reported for HIV-specific T cells. In this study, we examined the prevalence of these phenomena using 8-color cytokine flow cytometry, and tested the hypothesis that these two findings were causally related. We analyzed cytokine profiles and memory/effector phenotypes of HIV-specific and CMV-specific T cells using short-term in vitro stimulation with HIV or CMV peptide pools. Nineteen HIV-positive subjects with progressive disease and twenty healthy, HIV-negative subjects were examined. RESULTS: Among HIV-infected subjects, there were significantly fewer CD8+ IL-2+ T cells responding to HIV compared to CMV, with no significant difference in CD4+ IL-2+ T cells. The majority of CMV-specific T cells in both HIV-negative and HIV-positive subjects appeared to be terminally differentiated effector cells (CD8+ CD27- CD28- CD45RA+ or CD8+ CD27- CD28- CD45RA-). In HIV-positive subjects, the most common phenotype of HIV-specific T cells was intermediate in differentiation (CD8+ CD27+ CD28- CD45RA-). These differences were statistically significant, both as absolute cell frequencies and as percentages. There was a significant correlation between the absolute number of HIV-specific CD8+ IL-2+ T cells and HIV-specific CD8+ CD27- CD28- CD45RA+ terminal effector cells. CONCLUSION: IL-2 production from antigen-specific CD8+ T cells correlates with effector cell differentiation of those cells

Loss of Receptor on Tuberculin-Reactive T-Cells Marks Active Pulmonary Tuberculosis

BACKGROUND: Tuberculin-specific T-cell responses have low diagnostic specificity in BCG vaccinated populations. While subunit-antigen (e.g. ESAT-6, CFP-10) based tests are useful for diagnosing latent tuberculosis infection, there is no reliable immunological test for active pulmonary tuberculosis. Notably, all existing immunological tuberculosis-tests are based on T-cell response size, whereas the diagnostic potential of T-cell response quality has never been explored. This includes surface marker expression and functionality of mycobacterial antigen specific T-cells. METHODOLOGY/PRINCIPAL FINDINGS: Flow-cytometry was used to examine over-night antigen-stimulated T-cells from tuberculosis patients and controls. Tuberculin and/or the relatively M. tuberculosis specific ESAT-6 protein were used as stimulants. A set of classic surface markers of T-cell naive/memory differentiation was selected and IFN-gamma production was used to identify T-cells recognizing these antigens. The percentage of tuberculin-specific T-helper-cells lacking the surface receptor CD27, a state associated with advanced differentiation, varied considerably between individuals (from less than 5% to more than 95%). Healthy BCG vaccinated individuals had significantly fewer CD27-negative tuberculin-reactive CD4 T-cells than patients with smear and/or culture positive pulmonary tuberculosis, discriminating these groups with high sensitivity and specificity, whereas individuals with latent tuberculosis infection exhibited levels in between. CONCLUSIONS/SIGNIFICANCE: Smear and/or culture positive pulmonary tuberculosis can be diagnosed by a rapid and reliable immunological test based on the distribution of CD27 expression on peripheral blood tuberculin specific T-cells. This test works very well even in a BCG vaccinated population. It is simple and will be of great utility in situations where sputum specimens are difficult to obtain or sputum-smear is negative. It will also help avoid unnecessary hospitalization and patient isolation

A Proposed Mechanism for Congenitally Missing Teeth: Basic and Clinical Evidence

Introduction: Although the de-velopment of normal dentition has been explored extensively, the mechanisms underlying congenitally missing teeth are far less understood.The hypothesis: Congenital absence of teeth occurs due to arrested development of a tooth primordium followed by involution, only at a stages preceding mineralized tissue formation.Evaluation of the hypothesis: We compared H & E stained serial sagittal sections of wild-type and EL mice that are congenitally missing 3rd molars (3M). 3M development was followed longitudinally in both types of mice. Occurrence of apoptosis was examined using a fluorescent TUNEL assay. To determine if a similar process might account for congenital ab-sence of human teeth, we examined serial radiographs of developing dentitions. In EL mice, congenital absence of 3M is caused, not by a failure of initiation of tooth development rather; tooth development is initiated and subsequently ar-rested during early cap stage. This arrested tooth primordium is subsequently removed physiologically by apoptosis. Examination of serial radiographs where missing teeth were identified lent further evi-dence to support this hypothesis. Follicle spaces, with no calcified tissue within them, were noted at early stages which were seen to remodel and eventually blend with adjacent bone. Permanent teeth failed to develop in those locations. Based on the animal and human data, we propose a new model for congenital absence of teeth. Validation of this model could have profound clinical implications. If the genetic me-chanisms involved in this proposed mechanism can be elucidated, it might lead to non-surgical management of supernumerary teeth

The phenotypic distribution and functional profile of tuberculin-specific CD4 T-cells characterizes different stages of TB infection

BACKGROUND: Recent publications have suggested that altered proportions of functional CD4 T-cell subsets correlate with active pulmonary TB. Also, CD27-expression on tuberculin-activated IFN-gamma(+) CD4 T-cells is known to differ significantly between patients with active pulmonary TB and healthy TB-unexposed BCG vaccinees. Here, we explore links between CD4 T-cell phenotype, multiple functional subsets, and control of TB. METHODS: We examined ex-vivo overnight tuberculin activated CD4 T-cells in regards to CD27-expression and the activation markers, CD154 upregulation, IFN-gamma, TNF-alpha, IL-2, and degranulation in 44 individuals, including cases of clinically active pulmonary TB, and hospital staff with prolonged TB exposure, some of whom had latent TB. RESULTS: Active pulmonary TB generally showed an excess of TNF-alpha(+) subsets over IFN-gamma(+) subsets, paralleled by decreased CD27 expression on activated IFN-gamma(+) or CD154(+) CD4 T-cells. The single subset distinguishing best between active pulmonary TB and high TB exposure was CD154(+) /TNF-alpha(+) / IFN-gamma(-) /IL-2(-) /degranulation(-) (AUROC 0.90). The ratio between the frequencies of TNF-alpha(+) /IFN-gamma(+) CD4 T-cells was an effective alternative parameter (AUROC 0.87). CONCLUSIONS: Functional subsets and phenotype of tuberculin induced CD4 T-cells differ between stages of TB infection. Predominance of TNF-alpha(+) CD4 T-cells in active infection suggests an increased effort of the immune system to contain disease. (c) 2012 International Clinical Cytometry Society

Tuberculin-Specific T Cells Are Reduced in Active Pulmonary Tuberculosis Compared to LTBI or Status Post BCG Vaccination

Functional characteristics of tuberculosis (TB)–specific CD4 T cells were studied in clinically active pulmonary TB (n = 21) and high TB exposure including LTBI (n = 17). Following tuberculin stimulation, activated CD4 T cells were identified by flow-cytometry (CD154 up-regulation, degranulation, interferon γ [IFN-γ], tumor necrosis factor α [TNF-α], and interleukin 2 [IL-2\ production). Interestingly, CD154 up-regulation accounted for ∼80% of activated CD4 T cells in the active TB group but just 40% in the controls, whereas IFN-γ accounted for only ∼50% of activated cells in each group. The frequencies of CD4 T cells displaying at least 1 activation marker discriminated better between the groups than those displaying degranulation or IFN-γ production alone

Significantly fewer tuberculin-reactive CD4 T-cells express CD27 in TB-patients than in controls.

<p>Proportions of CD27-positive and negative cells were based on a minimum of 50 IFN-γ positive events. Vertical numbers indicate evaluated events (median and range). Controls included unexposed controls, professionally TB-exposed health care workers, and donors with latent infection. A threshold of 49% would effectively discriminate between patients and controls (dotted line). Controls with latent TB infection had higher values than individuals with no known exposure to TB.</p

CD27 expression on tuberculin-reactive CD4 T-cells reverts very slowly .

<p>A: CD27-expression on tuberculin-reactive CD4 T-cells was plotted against the length of the interval between the collection date of the analyzed blood sample and the collection date of the last positive sputum sample (all data from blinded study). Negative values indicate that sputum was already smear and culture negative when tuberculin-reactive CD4 T-cells were analyzed, positive values indicate that sputum samples were still positive and remained so for the indicated time. B: serial measurements in 7 individuals (data analysis blinded).</p

Crosstabulation of results in blind study.

<p>Crosstabulation of results in blind study.</p