Change of Th0 to Th1 cell-cytokine profile following tuberculosis chemotherapy

A whole blood assay as a simple, broad assessment of cytokines and chemokines to evaluate human immune responses to Mycobacterium tuberculosis antigens

In vitro stimulation of whole blood or isolated peripheral blood cells with specific antigens is used for several purposes. We sought to identify a reliable, reproducible, fast and feasible in vitro method to assess human cellular immune responses to Mycobacterium tuberculosis. In contrast to peripheral blood mononuclear cell (PBMC) culture, a whole blood assay (WBA) provides a more physiological environment, which may provide a broader assessment of serum biomarker, biosignature profiles. Twenty-three asymptomatic individuals with M. tuberculosis infection were recruited. Total cells from the WBA (diluted 1:3 in completed RPMI) and PBMC (2×10(5)cells/ml) plus M. tuberculosis Ag85A, Ag85B, ESAT-6 and Mycobacterium bovis 65kDa were characterized by flow cytometry, then added in 96-well plates and on day 5 plasma and supernatants were harvested for detection of 17 cytokines by a Luminex array system. There was agreement between PBMC and WBA for IL-2, IL-5, IL-6, IL-7, IL-13, IFN-γ, TNF-α, MCP-1 and MIP-1β. There was evidence toward higher IL-10 (p≤0.049) and G-CSF (p≤0.012) plasma production, and higher IL-1β (p≤0.048), IL-4 (p≤0.044), IL-12p70 (p≤0.006), IL-17 (p≤0.002) and GM-CSF (p≤0.049) production for PBMC vs. WBA. Both methods provided virtually no reaction to the internal, negative control. Due to technical issues linked to data out of range, IL-8 data were not considered. These results suggest that, depending on the method employed, PBMC and/or WBA techniques provide fine conditions for the model proposed and thus whole blood cultures are well-suited low-cost proxy-measures during search for serum biomarkers.

Simian immunodeficiency virus-induced changes in T cell cytokine responses in cynomolgus macaques with latent Mycobacterium tuberculosis infection are associated with timing of reactivation

Understanding the early immunologic events accompanying reactivated tuberculosis (TB) in HIV-infected individuals may yield insight into causes of reactivation and improve treatment modalities. We used the cynomolgus macaque (Macaca fascicularis) model of HIV-Mycobacterium tuberculosis coinfection to investigate the dynamics of multifunctional T cell responses and granuloma T cell phenotypes in reactivated TB. CD4(+) and CD8(+) T cells expressing Th1 cytokines (IFN-γ, IL-2, TNF) and Th2 cytokines (IL-4 and IL-10) were followed from latent M. tuberculosis infection to reactivation after coinfection with a pathogenic SIV. Coinfected animals experienced increased Th1 cytokine responses to M. tuberculosis Ags above the latent-response baseline 3-5 wk post-SIV infection that corresponded with peak plasma viremia. Th2 cytokine expression was not Ag specific, but strong, transient IL-4 expression was noted 4-7 wk post-SIV infection. Animals reactivating <17 wk post-SIV infection had significantly more multifunctional CD4(+) T cells 3-5 wk post-SIV infection and more Th2-polarized and fewer Th0-, Th1-polarized CD8(+) T cells during weeks 1-10 post-SIV infection than animals reactivating >26 wk post-SIV infection. Granuloma T cells included Th0-, Th1-, and Th2-polarized phenotypes but were particularly rich in cytolytic (CD107(+)) T cells. When combined with the changes in peripheral blood T cells, these factors indicate that events during acute HIV infection are likely to include distortions in proinflammatory and anti-inflammatory T cell responses within the granuloma that have significant effects on reactivation of latent TB. Moreover, it appears that mycobacteria-specific multifunctional T cells are better correlates of Ag load (i.e., disease status) than of protection.

[Tuberculosis in patients with asthma]

INTRODUCTION

The association of asthma and tuberculosis is rare but may raise particular issues around patient management. The aim of this study was to evaluate the clinical, therapeutic and progress of this association.

PATIENTS AND METHODS

We describe a retrospective study, which included seven asthmatic patients hospitalized for pulmonary tuberculosis during the period between June 2001 and June 2006.

RESULTS

Five men and two women were included. Mean age was 37 years. Two patients had mild asthma, four had moderate asthma and one had severe and corticosteroid-dependant asthma. Only four patients had controlled asthma when tuberculosis diagnosis was established. Asthma treatment was based on inhaled corticoids and long-acting beta-2-agonists. During antituberculosis treatment two patients developed near fatal asthma. Long-term stable asthma control was achieved over a time course of 3 to 8 years.

CONCLUSION

The association of asthma and tuberculosis can lead to potential therapeutic difficulties because of pharmacologic interactions between antituberculosis therapies and treatments for asthma treatment. In addition asthma following treatment for tuberculosis appears to be well controlled.

Analysis of Mycobacterium tuberculosis-specific CD8 T-cells in patients with active tuberculosis and in individuals with latent infection

CD8 T-cells contribute to control of Mycobacterium tuberculosis infection, but little is known about the quality of the CD8 T-cell response in subjects with latent infection and in patients with active tuberculosis disease. CD8 T-cells recognizing epitopes from 6 different proteins of Mycobacterium tuberculosis were detected by tetramer staining. Intracellular cytokines staining for specific production of IFN-γ and IL-2 was performed, complemented by phenotyping of memory markers on antigen-specific CD8 T-cells. The ex-vivo frequencies of tetramer-specific CD8 T-cells in tuberculous patients before therapy were lower than in subjects with latent infection, but increased at four months after therapy to comparable percentages detected in subjects with latent infection. The majority of CD8 T-cells from subjects with latent infection expressed a terminally-differentiated phenotype (CD45RA⁺CCR7⁻). In contrast, tuberculous patients had only 35% of antigen-specific CD8 T-cells expressing this phenotype, while containing higher proportions of cells with an effector memory- and a central memory-like phenotype, and which did not change significantly after therapy. CD8 T-cells from subjects with latent infection showed a codominance of IL-2⁺/IFN-γ⁺ and IL-2⁻/IFN-γ⁺ T-cell populations; interestingly, only the IL-2⁺/IFN-γ⁺ population was reduced or absent in tuberculous patients, highly suggestive of a restricted functional profile of Mycobacterium tuberculosis-specific CD8 T-cells during active disease. These results suggest distinct Mycobacterium tuberculosis specific CD8 T-cell phenotypic and functional signatures between subjects which control infection (subjects with latent infection) and those who do not (patients with active disease).

A case of immunoglobulin G4-related chronic sclerosing sialadenitis and dacryoadenitis associated with tuberculosis

We describe a 64-year-old woman with chronic sclerosing sialadenitis and dacryoadenitis, which developed during treatment for cervical lymph node tuberculosis. Anti-tuberculosis treatment did not improve the swelling in the lacrimal and submandibular glands, and a biopsy specimen of the lacrimal gland showed inflammation, with abundant lymphoid follicles with fibrosis and granuloma without caseous necrosis. Immunohistological examination of a repeat biopsy specimen showed abundant immunoglobulin (Ig) G4-positive plasma cell infiltration. Corticosteroid therapy improved the salivary gland swelling without reactivation of the tuberculosis. This case suggests that an abnormal immunological reaction to tuberculosis may be one of the etiological candidates for IgG4-related disease.

Protective immunity to Mycobacterium tuberculosis infection by chemokine and cytokine conditioned CFP-10 differentiated dendritic cells

Background

Dendritic cells (DCs) play major roles in mediating immune responses to mycobacteria. A crucial aspect of this is the priming of T cells via chemokines and cytokines. In this study we investigated the roles of chemokines RANTES and IP-10 in regulating protective responses from Mycobacterium tuberculosis (M. tb) 10 kDa Culture Filtrate Protein-10 (CFP-10) differentiated DCs (CFP10-DCs).

Methods and Findings

Infection of CFP10-DCs with mycobacteria down-modulated RANTES and IP-10 levels. Pathway specific microarray analyses showed that in addition to RANTES and IP-10, mycobacteria infected CFP10-DCs showed reduced expression of many Th1 promoting chemokines and chemokine receptors. Importantly, T cells co-cultured with RANTES and IP-10 conditioned CFP10-DCs mediated killing of mycobacteria from infected macrophages. Similarly, T cells recruited by RANTES and IP-10 conditioned CFP10-DCs mediated significant killing of mycobacteria from infected macrophages. IFN-gamma treatment of CFP10-DCs restored RANTES and IP-10 levels and T cells activated by these DCs mediated significant killing of virulent M. tb inside macrophages. Adoptive transfer of either RANTES and IP-10 or IL-12 and IFN-gamma conditioned CFP10-DCs cleared an established M. tb infection in mice. The extent of clearance was similar to that obtained with drug treatment.

Conclusions

These results indicate that chemokine and cytokine secretion by DCs differentiated by M. tb antigens such as CFP-10 play major roles in regulating protective immune responses at sites of infection.

An evaluation of commercial fluorescent bead-based luminex cytokine assays

The recent introduction of fluorescent bead-based technology, allowing the measurement of multiples analytes in a single 25-50 microl sample has revolutionized the study of cytokine responses. However, such multiplex approaches may compromise the ability of these assays to accurately measure actual cytokine levels. This study evaluates the performance of three commercially available multiplex cytokine fluorescent bead-based immunoassays (Bio-Rad's Cytokine 17-plex kit; LINCO Inc's 29-plex kit; and RnD System's Fluorokine-Multi Analyte Profiling (MAP) base kit A and B). The LINCO Inc kit was found to be the most sensitive assay for measuring concentrations of multiple recombinant cytokines in samples that had been spiked with serial dilutions of the standard provided by the manufacturer, followed respectively by the RnD Fluorokine-(MAP) and Bio-Rad 17-plex kits. A positive correlation was found in the levels of IFN-gamma measured in antigen stimulated whole blood culture supernatants by the LINCO Inc 29-plex, RnD Fluorokine-(MAP) and RnD system IFN-gamma Quantikine ELISA kits across a panel of controls and stimulated samples. Researchers should take the limitation of such multiplexed assays into account when planning experiments and the most appropriate use for these tests may currently be as screening tools for the selection of promising markers for analysis by more sensitive techniques.

Gene expression profiles of bronchoalveolar cells in pulmonary TB

The host response to Mycobacterium tuberculosis includes macrophage activation, inflammation with increased immune effector cells, tissue necrosis, and cavity formation, and fibrosis, distortion, and bronchiectasis. To evaluate the molecular basis of the immune response in the lungs of patients with active pulmonary tuberculosis (TB), we used bronchoalveolar lavage to obtain cells at the site of infection. Affymetrix GeneChip microarrays and cDNA nylon filter microarrays interrogated gene expression in bronchoalveolar lavage (BAL) cells from 11 healthy controls and 17 patients with active pulmonary TB. We found altered gene expression for 69 genes in TB versus normal controls that included cell surface markers, cytokines, chemokines, receptors, transcription factors, and complement components. In addition, TB BAL cell gene expression patterns segregated into 2 groups: one suggestive of a T helper type 1 (Th1) cellular immune response with increased signal transducer and activator of transcription-4 (STAT-4), interferon-gamma (IFN-gamma receptor), and monokine induced by IFN-gamma (MIG) expression with increased IFN-gamma protein levels in BAL fluid; the other group displayed characteristics of Th2 immunity with increased STAT-6, CD81, and IL-10 receptor expression. We were able to demonstrate that a Th2 presentation could change to a Th1 pattern after anti-tuberculous treatment in 1 TB patient studied serially. These gene expression data support the conclusion that pulmonary TB produces a global change in the BAL cell transcriptome with manifestations of either Th1 or Th2 immunity.

IL-4 depletion enhances host resistance and passive IgA protection against tuberculosis infection in BALB/c mice

The influence of Th2 cytokines in tuberculosis has been a matter of dispute. Here we report that IL-4 has a profound regulatory effect on the infection of BALB/c mice with Mycobacterium tuberculosis. Depletion of IL-4 with a neutralizing mAb caused only evanescent reduction of lung infection, but when combined with i.n. inoculations of IgA anti-mycobacterial alpha-crystallin mAb and mouse rIFN-gamma, we observed a 40-fold reduction of the bacterial counts in the lungs at 3 wks following i.n. infection (p<0.001). In genetically deficient IL-4-/- BALB/c mice, infection in both lung and spleen was substantially reduced for up to 8 wks without further treatment. Reconstitution of IL-4-/- mice with rIL-4 increased bacterial counts to wild-type levels and made the mice refractory to protection by IgA/IFN-gamma. Analysis of the lungs showed increased granulomatous infiltration and proinflammatory mediators in anti-IL-4/IgA/IFN-gamma-treated and infected mice. We conclude that the action of IL-4 in tuberculosis is targeted at macrophages and that it may include an antagonistic effect on their IgA/IFN-gamma-induced activation and nitric oxide production. The described novel immunotherapy, combining treatments with anti-IL-4, IgA antibody and IFN-gamma, has potential for translation toward the passive immunoprophylaxis of tuberculosis.

Plasma granulysin levels and cellular interferon-gamma production correlate with curative host responses in tuberculosis, while plasma interferon-gamma levels correlate with tuberculosis disease activity in adults

Granulysin is a recently identified cytolytic protein which is expressed by human cytotoxic T-lymphocytes and natural killer (NK)-cells, and has broad antimicrobial and tumoricidal activity. Circulating granulysin levels are associated with T- and NK-cell activity, and may thus reflect protection-associated cellular immune responses. In a case-control study in Indonesia, a highly tuberculosis (TB)-endemic country, we therefore determined plasma granulysin levels in adults with active pulmonary TB before, during, and after TB treatment, both in mild/moderate-TB and advanced-TB patients, and compared these to healthy neighbourhood controls. Adults with active pulmonary TB had significantly lower plasma granulysin levels compared to controls. After 2 months of anti-TB therapy, levels in TB patients had significantly increased, reaching values similar to those in controls. Plasma granulysin levels further increased after completion of TB therapy, being significantly higher than those in controls. Plasma granulysin levels correlated inversely with TB disease activity but not with TB disease severity. In contrast, plasma interferon-gamma (IFN-gamma) levels were significantly higher in active TB cases than in controls, normalised during treatment and correlated with both TB disease activity and TB disease severity. At the cellular level, granulysin and IFN-gamma expression both correlated inversely with disease activity. Interestingly, granulysin was predominantly expressed by IFN-gamma negative T-cells, suggesting that the cellular sources of IFN-gamma and granulysin in TB are partly non-overlapping. The observation that plasma granulysin levels and cellular IFN-gamma production correlate with curative host responses in pulmonary tuberculosis points to a potentially important role of granulysin, next to IFN-gamma, in host defence against M. tuberculosis.

T-cell recognition of the HspX protein of Mycobacterium tuberculosis correlates with latent M. tuberculosis infection but not with M. bovis BCG vaccination

During stationary growth or in vitro conditions mimicking relevant aspects of latency, the HspX protein (Rv2031c) is specifically upregulated by Mycobacterium tuberculosis. In this study we compared T-cell responses against HspX and the secreted M. tuberculosis protein Ag85B (Rv1886c) in tuberculosis (TB) patients, tuberculin skin test-positive individuals, M. bovis BCG-vaccinated individuals, and healthy negative controls. Gamma interferon responses to HspX were significantly higher in M. tuberculosis-exposed individuals than in M. tuberculosis-unexposed BCG vaccinees. In contrast, no such differences were found with respect to T-cell responses against Ag85B. Therefore, BCG-based vaccines containing relevant fragments of HspX may induce improved responses against this TB latency antigen. To identify relevant major histocompatibility complex class I- and class II-restricted HspX-specific T-cell epitopes, we immunized HLA-A2/K(b) and HLA-DR3.Ab(0) transgenic (tg) mice with HspX. Two new T-cell epitopes were identified, p91-105 and p31-50, restricted via HLA-A*0201 and HLA-DRB1*0301, respectively. These epitopes were recognized by human T cells as well, underlining the relevance of HspX T-cell recognition both in vivo and in vitro. In line with the data in humans, BCG immunization of both tg strains did not lead to T-cell responses against HspX-derived epitopes, whereas nonlatency antigens were efficiently recognized. These data support the notion that BCG vaccination per se does not induce T-cell responses against the latency antigen, HspX. Thus, we suggest that subunit vaccines incorporating HspX and/or other latency antigens, as well as recombinant BCG strains expressing latency antigens need to be considered as new vaccines against TB.

Cytokine Profile of T lymphocytes from Peripheral Blood and Bronchoalveolar Lavage Fluid in Patients with Active Pulmonary Tuberculosis

The possible immunological relationship between the pattern of Th1/Th2 cytokine production and tuberculin reactivity was assessed in patients with active Mycobacterium tuberculosis infection. The production of the intracellular cytokines interferon (IFN)-gamma and interleukin-4 (IL-4) was measured in CD4(+) and CD8(+) T cells obtained from peripheral blood and bronchoalveolar lavage fluid (BALF) of 20 tuberculin skin-positive patients and compared with the findings recorded in nine tuberculin skin-negative patients with active pulmonary tuberculosis. Upon stimulation with phorbol 12-myristate acetate/ionomycin for 6 h, tuberculin-negative patients had a significantly higher proportion of IFN-gamma-producing CD4(+) T lymphocytes in BALF than in peripheral blood, while both CD4(+) and CD8(+) T-lymphocyte subsets in BALF of tuberculin-positive patients secreted more IFN-gamma than their peripheral blood counterparts. Tuberculin-negative patients had a significantly higher proportion of IFN-gamma-producing CD4(+) T lymphocytes in peripheral blood than tuberculin-positive patients. There was no significant difference in the production of IFN-gamma by BALF CD4(+) T lymphocytes, or by either peripheral blood or BALF CD8(+) T lymphocytes. In two tuberculin-negative patients, peripheral blood CD4(+) T lymphocytes produced IL-4. Study results suggested a higher immune activity in the blood of tuberculin-negative patients, with an increased lymphocyte activity in BALF versus peripheral blood in both patient groups.

Subcutaneously administered interferon-gamma for the treatment of multidrug-resistant pulmonary tuberculosis

OBJECTIVE

We evaluated the clinical and laboratory effects of subcutaneously administered interferon-gamma (IFN-gamma) in the treatment of chronic and advanced multidrug-resistant tuberculosis (MDR-TB).

DESIGN

Eight patients with sputum smear and culture persistently positive MDR-TB were subcutaneously administered 2 million international units of recombinant human IFN-gamma three times a week for 24 weeks (72 doses total) between December 2002 and May 2003. Subjects also received a customized drug regimen containing second- and third-line antituberculosis agents based upon drug susceptibility testing and previous treatment history.

RESULTS

Body weight remained stable or slightly decreased in all subjects during the study period, and none displayed radiographic improvement on serial chest computed tomography scanning. Sputum smears and cultures remained positive for all patients, and there was no increase in the mean time to yield a positive culture (from 16.5+/-6.4 to 11.8+/-4.9 days). There was no enhancement of cell-mediated immune responses in terms of production of IFN-gamma or IL-10, or of composition of lymphocytes among peripheral blood mononuclear cells. In four patients, therapy was discontinued because of adverse reactions.

CONCLUSION

In patients with chronic and advanced MDR-TB, subcutaneous IFN-gamma treatment did not result in improvement in clinical, radiologic, microbiologic, or immunologic parameters.

Th0 to Th1 switch of CD4 T cell clones specific from the 16-kDa antigen of Mycobacterium tuberculosis after successful therapy: lack of involvement of epitope repertoire and HLA-DR

In this study, we have examined the influence of HLA-DR molecules and the structure of the epitope repertoire of the 16-kDa protein of Mycobacterium tuberculosis on the acquisition of the cytokine secretion pattern of CD4 T cell clones, obtained from tuberculous patients before and after anti-mycobacterial therapy. Our data indicate that TB patients have a predominant Th0 response against the 16-kDa protein and its epitopes and that healing, induced by anti-mycobacterial therapy, is associated with a shift toward a predominant Th1 phenotype. Moreover, both HLA-DR molecules restricting the clone specificity and the nature of the recognized epitope do not play any role in the generation of Th0 and Th1 clones. These findings indicate that additional factors, such as the cytokine environment and/or costimulatory molecules, determine the Th phenotype of CD4 T cells during tuberculosis.

In vitro T-cell immunogenicity of oligopeptides derived from the region 92-110 of the 16-kDa protein ofMycobacterium tuberculosis

The 16-kDa protein of Mycobacterium tuberculosis provokes specific immune responses; it is thus a target for the development of peptide-based diagnostic reagents and subunit vaccines. Previous studies have demonstrated the presence of several regions containing murine and human T-cell epitopes. Within the 91-110 immunodominant domain, we found that peptides comprising the sequence of 91SEFAYGSFVRTVSL104 elicit specific T-cell responses in both human T-cell clones and human peripheral blood mononuclear cells (PBMC) from PPD+ (purified protein derivative) individuals. Elongation of this peptide towards the C-terminal end did not provide more effective peptides, but the removal of residue 91Ser resulted in an almost complete loss of functionality. However, the introduction of an acetyl group at the N-terminal of residue 92Glu produced a shorter peptide (Ac-92EFAYGSFVRTVSL104) exhibiting properties required for efficient T-cell responses. CD measurements indicated that peptide 91SEFAYGSFVRTVSLPVGADE110 adopts a helical conformation in trifluoroethanol. We found that the N-terminal part of this sequence plays a major role in the induction of proliferative T-cell responses and is responsible for the highly ordered, helical secondary structure. The "lead" structure described here could also be considered in the development of synthetic peptides or multicomponent peptide mixtures for the early detection, monitoring, or preventing Mycobacterium tuberculosis infection with optimized T-cell response-provoking capacity.

Therapeutic effect of DNA vaccines combined with chemotherapy in a latent infection model after aerosol infection of mice with Mycobacterium tuberculosis

The prevention of Mycobacterium tuberculosis (M. tuberculosis) reactivation would greatly reduce the incidence of the disease, particularly among the elderly. Here, we evaluated the efficacy of DNA vaccine in combination with a conventional TB chemotherapy on the prevention of M. tuberculosis reactivation. Mice were treated with isoniazid and pyrazinamide for 3 months from 4 weeks after aerosol infection with M. tuberculosis H37Rv. During this period of chemotherapy, DNA immunization was performed three times monthly with an antigen 85A (Ag85A) DNA or an IL-12 mutant (IL-12N220L) DNA, which is known to lead to a reduction in the secretion of the p40 subunit, but not of a bioactive IL-12p70. The reactivation of M. tuberculosis was dramatically reduced in mice treated with either Ag85A DNA (P<0.01) or IL-12N220L DNA (P<0.05) in combination with chemotherapy, compared with control mice receiving only chemotherapy. Ag85A DNA vaccine showed higher IFN-gamma responses to Ag85A protein, but a lower response to culture filtrate than IL-12N220L DNA vaccine. In addition, Ag85A DNA vaccine prevented the reactivation of M. tuberculosis more efficiently than IL-12N220L DNA vaccine, indicating that Ag85A-specific IFN-gamma response might correlate with M. tuberculosis control. This study suggests that immunotherapy using Ag85A or IL-12N220L DNA vaccine combined with conventional chemotherapy might be effective clinically for the prevention of tuberculosis reactivation and may offer a more effective cure for humans than chemotherapy alone.

Cytokine profile, HLA restriction and TCR sequence analysis of human CD4+ T clones specific for an immunodominant epitope of Mycobacterium tuberculosis 16-kDa protein

The identification of immunodominant and universal mycobacterial peptides could be applied to vaccine design and have an employment as diagnostic reagents. In this paper we have investigated the fine specificity, clonal composition and HLA class II restriction of CD4+ T cell clones specific for an immunodominant epitope spanning amino acids 91-110 of the 16-kDa protein of Mycobacterium tuberculosis. Twenty-one of the tested 28 clones had a Th1 profile, while seven clones had a Th0 profile. None of the clones had a Th2 profile. While the TCR AV gene usage of the clones was heterogeneous, a dominant TCR BV2 gene family was used by 18 of the 28 clones. The CDR3 regions of BV2+ T cell clones showed variation in lengths, but a putative common motif R-L/V-G/S-Y/W-E/D was detected in 13 of the 18 clones. Moreover, the last two to three residues of the putative CDR3 loops, encoded by conserved BJ sequences, could also play a role in peptide recognition. Antibody blockade and fine restriction analysis using HLA-DR homozygous antigen-presenting cells established that 16 of 18 BV2+ peptide-specific clones were DR restricted and two clones were DR-DQ and DR-DP restricted. Additionally, five of the 18 TCRBV2+ clones recognized peptide 91-110 in association with both parental and diverse HLA-DR molecules, indicating their promiscuous recognition pattern. The ability of peptide 91-110 to bind a wide range of HLA-DR molecules, and to stimulate a Th1-type interferon (IFN)-gamma response more readily, encourage the use of this peptide as a subunit vaccine component.

Cytokine production and expression of leucocyte-differentiation antigens by human mononuclear cells in response to mycobacterium tuberculosis antigens

The aim of this work was to characterize a leucocyte-differentiation antigen or chemokine receptor that allows the identification of type 1 (T helper 1 (Th1), Tc1) and type 2 (Th2, Tc2) lymphocytes in short-term-cultured human peripheral blood mononuclear cells. In addition, we assessed the type of response induced by mycobacterial antigens in tuberculosis patients and healthy contacts. Cells were stimulated with an unfractionated culture filtrate or 30 kDa antigen from Mycobacterium tuberculosis. Then, CD4 and CD8 cell labelling was combined with CD30, CD27, CD28, CD45RA or CD45R0 staining, detection of intracellular interferon-gamma (IFN-gamma) or interleukin-4 (IL-4) and analysis by three-colour flow cytometry. In separate experiments, the expression of different chemokine receptors (CCR1, CCR3, CCR5, CXCR3 and CXCR4) was also studied. We found that none of the cell-surface molecules studied was preferentially expressed by Th1 or Th2 cells. Thus, our results indicate that these lymphocyte subsets cannot be identified in short-term-cultured mononuclear cells on the basis of preferential expression of the cell markers studied, and that it is necessary to look for additional molecules that allow the discrimination of Th1 and Th2 cells.

Influence of Mycobacterium tuberculosis on differential activation of helper T-cells

Host defence against tuberculosis infection involves T-lymphocyte mediated cellular immune responses. In this study we assessed T-cell activation by studying the early signal transduction events and production of cytokines by human CD4+ T-cells. The study constituted of five groups of subjects: (a) untreated acid fast bacilli (AFB)+ve TB patients who have not started anti-tuberculosis therapy (ATT) [New]; (b) patients who have taken ATT for two months [2T]; (c) patients who have taken ATT for six months [6T]; (d) mantoux positive healthy controls [T+ve]; (e) mantoux negative healthy controls [T-ve]. We found that mantoux positive healthy controls produced significantly higher levels of IP3, intracellular Ca2+ and presented increased PKC activity when CD4+ T-cells were stimulated with M. tuberculosis H37Rv cell lysate as compared to mantoux negative controls. Furthermore, decreased expression of CD54 (ICAM-1) and reduced [Ca2+]i were seen in TB patients as compared to T+ve healthy controls. TB patients showed significantly lower levels of IL-2 and IFNgamma and higher levels of IL-4 as compared to normal healthy controls, suggesting a diminished Th1 response. Thus, the reciprocal changes in cytokines, reduced [Ca2+]i levels, and CD54 expression in patients imply phenotype shifting of Th precursors to Th2 type in TB patients.

Selective T-cell recognition of the N-terminal peptide of GroES in tuberculosis

Peptides derived from the whole sequence of mycobacterial GroES heat shock proteins were tested for the ability to induce the proliferation of blood mononuclear cells from tuberculosis patients and sensitized healthy subjects. The response to the N-terminal peptide (residues 1 to 16) was found to be more frequent and stronger in tuberculosis patients. This finding is exceptional, considering that recognition of all other GroES peptides by patients was either diminished or not different from that of controls.

Interleukin-4 and its alternatively spliced variant (IL-4delta2) in patients with atopic asthma

The interleukin-4 (IL-4) splice variant (IL-4delta2) is known to antagonize many biological activities of IL-4, and this challenges our understanding of the role of IL-4 in asthma. Studies that have used nonspecific antibodies, probes, and/or primers to quantify IL-4 in clinical samples would not have distinguished the expression of IL-4 from IL-4delta2. This is the first study to examine patients with chronic asthma and atopy for IL-4delta2 mRNA in their peripheral blood mononuclear cells without antigen stimulation, using a quantitative nested reverse-transcription polymerase chain reaction (RT-PCR) protocol. The median IL-4 mRNA copy number in cells from the patients with asthma was 2.8 logs higher than in a comparator group of patients with tuberculosis (p = 0.0005) and 4.5 logs higher (p = 0.0004) than in healthy control subjects. In contrast, IL-4delta2 expression in cells from patients with asthma was similar to that seen in cells from patients with tuberculosis. Hence, the median ratio of IL-4 to IL-4delta2 was 500-fold higher in the patients with asthma when compared with either patients with tuberculosis or healthy control subjects. The relative expression of IL-4 and IL-4delta2 may be a reason for the functional diversity of Th2 cells in different clinical conditions, and a hitherto unexplored mechanism for the pulmonary pathology in patients with atopic asthma.