Biomedical subjects

Z Toossi

Publications and source records attributed to Z Toossi.

At least 19 recordsLinked to original sources

PubMed2007

Intestinal helminth co-infection has a negative impact on both anti-Mycobacterium tuberculosis immunity and clinical response to tuberculosis therapy.

The impact of intestinal helminth infection on Mycobacterium tuberculosis (MTB)-specific immune responses during active tuberculosis (TB) is not known. We investigated the role of intestinal helminth infection in anti-MTB immunity by evaluating both cellular phenotype and cytokine profiles in patients with TB and patients with concomitant TB and intestinal helminth infection (TB + Helm) during TB therapy. Twenty-seven per cent of TB patients enrolled for the study were co-infected with at least one intestinal helminth. At baseline, absolute frequencies of leucocytes, monocytes and eosinophils from TB and TB + Helm patients differed from healthy subjects. Concomitant intestinal helminth infection in TB + Helm patients had a negative impact (P < 0.05) on absolute frequencies of CD3(+), CD4(+), CD8(+), natural killer (NK) T and CD4(+) CD25(high) T cell subsets when compared to either TB patients or healthy controls. Differences in CD4(+) T cell frequencies were accompanied by lower interferon (IFN)-gamma and elevated and sustained interleukin (IL)-10 levels in whole blood (WB) cultures from TB + Helm compared to TB patients. In addition to a depressed anti-MTB immunity, TB + Helm patients also presented with more severe radiological pulmonary disease, with a significant difference (P = 0.013) in the number of involved lung zones at the end of TB treatment. The above data may indicate that concomitant intestinal helminth infection in patients with newly diagnosed TB skews their cytokine profile toward a T helper 2 response, which could favour persistent MTB infection and a more protracted clinical course of the disease.

Adolescent↗

PubMed2006

A role for CD4+CD25+ T cells in regulation of the immune response during human tuberculosis.

Active tuberculosis (TB) is associated with prolonged suppression of Mycobacterium tuberculosis (MTB)-specific immune responses, but mechanisms involved are understood incompletely. We investigated a potential role for CD4+CD25+ regulatory T cells in depressed anti-MTB immunity by evaluating serially CD4 cell phenotype and interferon (IFN)-gamma production by mononuclear cells from patients with TB. At diagnosis, frequencies of CD4+CD25+ T cells were increased in blood from TB patients compared to healthy purified protein derivative (PPD)-positive controls (with a history of prior TB exposure), and remained elevated at completion of therapy (6 months). By contrast, expression of another activation marker, CD69, by CD4 T cells was increased at diagnosis, but declined rapidly to control levels with treatment. Among CD4+CD25+ T cells from TB patients at diagnosis those expressing high levels of CD25, probably representing regulatory T cells, were increased 2.9-fold when compared to control subjects, while MTB-stimulated IFN-gamma levels in whole blood supernatants were depressed. A role for CD4+CD25+ T cells in depressed IFN-gamma production during TB was substantiated in depletion experiments, where CD25+-depleted CD4 T cells produced increased amounts of IFN-gamma upon MTB stimulation compared to unseparated T cells. At follow-up, IFN-gamma production improved most significantly in blood from TB patients with high baseline frequencies of CD4+CD25+ T cells (more than threefold higher than controls for both total and CD25hi+ CD4 T cells), who also had a significant drop in frequencies of both total and 'regulatory' CD4+CD25+ T cells in response to treatment. Expansion of CD4+CD25+ regulatory T cells during active TB may play a role in depressed T cell IFN-gamma production.

Adult↗

PubMed2005

Inhibition of human immunodeficiency virus-1 (HIV-1) by beta-chemokine analogues in mononuclear cells from HIV-1-infected patients with active tuberculosis.

Tuberculosis (TB) enhances human immunodeficiency virus-1 (HIV-1) activity in patients with dual HIV-1/TB infection. Therapies that control augmentations of HIV-1 activity at sites of Mycobacterium tuberculosis (MTB) infection may be useful in inhibition of viral expansion. Regulated upon activation, normal T-cell expressed and secreted (RANTES) analogues (AOP and NNY) are potent in inhibiting the entry of primary HIV-1 isolates into host mononuclear cells. These analogues were used to inhibit MTB-induced HIV-1 entry in blood monunuclear cells (PBMC) from patients with pulmonary TB, and pleural fluid mononuclear cells (PFMC) from patients with pleural TB. PBMC or PFMC were cultured with and without MTB in presence and absence of RANTES analogues. HIV-1 strong stop DNA was assessed by real-time polymerase chain reaction (PCR) as a measure of infection. CCR5 mRNA was assessed by real-time reverse transcription (RT)-PCR and by immunostaining and FACS analysis. HIV-1 infection was induced by MTB in vitro in PBMC from the majority (14 of 20) of HIV-1/TB subjects, and new infection was inhibited by AOP- or NNY-RANTES. HIV-1 infection was also inhibited by these reagents in MTB-induced PFMC from three of three patients with pleural TB. Expression of CCR5 mRNA was significantly induced by MTB in PBMC from patients with pulmonary TB. Further, expression of CCR5 was higher in PFMC compared to PBMC from patients with pleural TB. Also, CCR5 was fourfold higher on CD14(+) pleural mononuclear cells than on CD4(+) lymphocytes. Blocking new HIV-1 infection of mononuclear cells may be useful in control of HIV-1 during dual HIV-1/TB infection.

Adult↗

PubMed2005

Bioactivation of latent transforming growth factor beta1 by Mycobacterium tuberculosis in human mononuclear phagocytes.

Biologically active transforming growth factor beta 1 (TGFbeta1) has been identified at sites of Mycobacterium tuberculosis (MTB) infection in the lung; however, the underlying mechanism(s) for its activation is not clear. Here using an enzyme-linked immunospot assay for TGFbeta1, we show that human blood monocytes (MN) and alveolar macrophages (AM) produce bioactive TGFbeta1 upon stimulation by MTB. However, only MTB-stimulated MN increased TGFbeta1 production on a per cell basis. The frequency of TGFbeta1-producing MN was reduced by an inhibitor of plasmin, bdellin, indicating a role for plasmin pathways in the bioactivation of cytokine. The expression of urokinase plasminogen activator receptor (uPAR) mRNA and both surface and soluble uPAR (CD87) was increased in MTB-activated MN. However, antibody neutralization of uPAR suppressed bioactive TGFbeta1 in MN alone. Thus, the more immature MN, which are continuously recruited to the lung during tuberculosis (TB), have a higher capacity to bioactivate TGFbeta1 by expression of components of the plasmin pathway. Excess production and bioactivation of TGFbeta1 at sites of MTB infection may undermine host immune responses during TB.

Adult↗

PubMed2004

Protective responses in tuberculosis: induction of genes for interferon-gamma and cytotoxicity by Mycobacterium tuberculosis and during human tuberculosis.

The host effector mechanisms against Mycobacterium tuberculosis infection are not well understood, and this remains a problem in the development of new vaccines and immunotherapies in tuberculosis (TB). Here, we studied the expression of genes for interferon gamma (IFN-gamma) and molecules involved in lymphocyte-mediated cytotoxicity [granzyme B (grzB), perforin, granulysin and Fas ligand (FasL)] against M. tuberculosis-infected macrophages. The kinetics of expression of these molecules were first established in peripheral blood mononuclear cells (PBMC) of healthy donors, and then investigated in TB patients with and without HIV-1 coinfection and appropriate control groups. We found that only IFN-gamma and grzB were induced by M. tuberculosis in PBMC from healthy purified protein derivative skin test reactive subjects. However, expression of neither gene nor IFN-gamma protein correlated with intracellular M. tuberculosis growth containment by macrophages. Mycobacterium tuberculosis induction of IFN-gamma, but not grzB, mRNA expression was significantly lower (P < 0.03) in TB patients as compared with healthy subjects.

Cytotoxicity, Immunologic↗

PubMed2001

Anatomically compartmentalized human immunodeficiency virus replication in HLA-DR+ cells and CD14+ macrophages at the site of pleural tuberculosis coinfection.

This study examined the impact of the host inflammatory microenvironment associated with localized tuberculosis (TB) on human immunodeficiency virus type 1 (HIV-1) replication within lymphocytes and macrophages in vivo. Paired plasma and pleural fluid samples from HIV-1-infected individuals with pleural TB (n=9) were analyzed. Detection of host proteins incorporated into the HIV-1 envelope by immunomagnetic capture analysis provided insight into the phenotype of cells supporting HIV-1 replication. The results indicated that the 4.0-fold greater median HIV-1 load in pleural fluid, compared with median load in plasma (P<.01), was derived in part from viral replication within HLA-DR+ cells, CD26+ lymphocytes, and, importantly, CD14+ macrophages. Greatly increased local concentrations of proinflammatory cytokines and immune activation markers in the pleural space correlated with the virologic findings. In summary, HIV-1 replication was increased at sites of Mycobacterium tuberculosis coinfection within activated cells, including lymphocytes and CD14+ macrophages.

AIDS-Related Opportunistic Infections↗

PubMed2001

Increased replication of HIV-1 at sites of Mycobacterium tuberculosis infection: potential mechanisms of viral activation.

Tuberculosis (TB) enhances HIV-1 replication and the progression to AIDS in dually infected patients. We employed pleural TB as a model to understand the interaction of the host with HIV-1 during active TB, at sites of Mycobacterium tuberculosis (MTB) infection. HIV-1 replication was enhanced both in the cellular (pleural compared with blood mononuclear cells) and acellular (pleural fluid compared with plasma) compartments of the pleural space. Several potential mechanisms for expansion of HIV-1 in situ were found, including augmentation in expression of tumor necrosis factor (TNF)-alpha and the HIV-1 noninhibitory beta-chemokine (MCP-1), low presence of HIV-1 inhibitory beta-chemokines (MIP-1 alpha, MIP-1 beta, and RANTES [regulated on activation, normal T expressed and secreted]), and upregulation in expression of the HIV-1 coreceptor, CCR5, by pleural fluid mononuclear cells. Thus, at sites of MTB infection, conditions are propitious both for transcriptional activation of HIV-1 in latently infected mononuclear cells, and facilitation of viral infection of newly recruited cells. These mechanisms may contribute to enhanced viral burden and dissemination during TB infection.

AIDS-Related Opportunistic Infections↗

PubMed2001

Activation of beta-chemokines and CCR5 in persons infected with human immunodeficiency virus type 1 and tuberculosis.

Tuberculosis (TB) in human immunodeficiency virus type 1 (HIV-1)-infected persons is associated with progression of HIV-1 disease. The expression of macrophage inflammatory protein (MIP)-1alpha and CCR5 was assessed in HIV-1-infected patients with pulmonary TB (HIV-1/PTB) and without PTB (HIV-1/C), PTB patients not infected with HIV-1 (PTB), and control subjects. Mycobacterium tuberculosis (MTB)-induced MIP-1alpha production was lower in peripheral blood mononuclear cells (PBMC) of HIV-1/PTB patients than in those of PTB patients (P< .05) and was lower in PBMC of HIV-1/C patients than in those of control subjects (P< .005). However, MIP-1alpha production was higher in PBMC of HIV/PTB patients than in those of HIV-1/C patients (P< .01). The pattern of MTB-induced RANTES production was similar to that of MIP-1alpha. However, MTB induced greater expression of mRNA for CCR5 in PBMC of HIV-1/PTB patients than in those of HIV-1/C patients (P< .04). Furthermore, the MTB-induced HIV p24 antigen level in PBMC of HIV-1/PTB patients with a CD4 cell count <500 cells/microL was higher (P< .05) than that in HIV-1/C patients. Thus, perturbations in chemokine pathways in HIV-1/PTB patients may accelerate HIV-1 disease.

AIDS-Related Opportunistic Infections↗

PubMed2001

Macrophage-activating cytokines in human immununodeficiency virus type 1-infected and -uninfected patients with pulmonary tuberculosis.

Tuberculosis (TB) is the most common opportunistic infection in human immunodeficiency virus type 1 (HIV-1)-infected patients globally and occurs throughout the course of HIV-1 disease. Here the production of interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha by peripheral blood mononuclear cells (PBMC) of HIV-1-infected versus -uninfected patients with newly diagnosed pulmonary TB (PTB) was compared. Findings were correlated with cytokine profiles, clinical presentation, and expression of inducible nitric oxide (iNOS). Most HIV-1/PTB patients with a CD4 cell count of 200-500 cells/microL had high IFN-gamma production and radiographic evidence of atypical PTB. Low IFN-gamma production and radiographic evidence of reactivated PTB characterized both HIV-1/PTB patients with a CD4 cell count >or=500 cells/microL and HIV-1-uninfected patients. TNF-alpha levels were similar in all HIV-1/PTB patients, regardless of CD4 cell count. Induction of iNOS in PBMC was low and was associated with low IFN-gamma production. These data underscore the potential pathogenic role of macrophage-activating cytokines in TB in HIV-1-infected patients.

AIDS-Related Opportunistic Infections↗

PubMed2001

Dysregulation of beta-chemokines in the lungs of HIV-1-infected patients.

The beta-chemokines, macrophage inflammatory protein (MIP)-1 alpha, MIP-1 beta, monocyte chemotactic protein (MCP)-1 and regulated-on-activation normal T cell, expressed and secreted (RANTES) are not only chemotactic for mononuclear cells but may be important in suppression of HIV-1 replication through competitive binding to the chemokine receptor, CCR5, which is critical to viral entry. In this study, bronchoalveolar cells (BACs) and autologous peripheral blood mononuclear cells (PBMCs) were obtained from HIV-1-infected participants who did not manifest clinical signs of lung disease with peripheral CD4 T-cell count >200/mm(3) (n = 7, group with high CD4 count), or CD4 T-cell count <200/mm(3) (n = 12, group with low CD4 count), and from healthy study subjects (n = 5). The capacity to express beta-chemokines and CCR5 was assessed. Induction of MIP-1 alpha by lipopolysaccharide (LPS) in BAC of HIV-1-infected study subjects from the low CD4 group was less than BAC from healthy study subjects (p <.001), and also was less than in BACs from the group with a high CD4 group (p <.001). Moreover, the intracellular expression of MIP-1 alpha in LPS-induced monocytes of HIV-1-infected patients was significantly less than that from healthy study subjects (p <.01). In addition, spontaneous expression of mRNAs for CCR5 and MIP-1 alpha in BAC was significantly lower in HIV-1-infected patients compared with in healthy study subjects (p <.03 and p <.02, respectively). In contrast to the findings with MIP-1 alpha, LPS stimulated MCP-1 in BAC from the group of HIV-1-infected patients with high CD4 count was significantly higher than healthy study subjects (p <.001). These dysregulations in the ability to express beta-chemokines by BAC may be important in the progression of HIV-1 infection in the lung.

Bronchoalveolar Lavage↗

PubMed2001

Augmentation of apoptosis and interferon-gamma production at sites of active Mycobacterium tuberculosis infection in human tuberculosis.

Pleural tuberculosis (TB) was employed as a model to study T cell apoptosis at sites of active Mycobacterium tuberculosis (MTB) infection in human immunodeficiency virus (HIV)-coinfected (HIV/TB) patients and patients infected with TB alone. Apoptosis in blood and in pleural fluid mononuclear cells and cytokine immunoreactivities in plasma and in pleural fluid were evaluated. T cells were expanded at the site of MTB infection, irrespective of HIV status. Apoptosis of CD4 and non-CD4 T cells in the pleural space occurred in both HIV/TB and TB. Interferon (IFN)-gamma levels were increased in pleural fluid, compared with plasma. Spontaneous apoptosis correlated with specific loss of MTB-reactive, IFN-gamma-producing pleural T cells. Immunoreactivities of molecules potentially involved in apoptosis, such as tumor necrosis factor-alpha, Fas-ligand, and Fas, were increased in pleural fluid, compared with plasma. These data suggest that continued exposure of immunoreactive cells to MTB at sites of infection may initiate a vicious cycle in which immune activation and loss of antigen-responsive T cells occur concomitantly, thus favoring persistence of MTB infection.

AIDS-Related Opportunistic Infections↗

PubMed2001

Impact of tuberculosis (TB) on HIV-1 activity in dually infected patients.

Active TB in HIV-1-infected subjects is associated with increased HIV-1-related immunodeficiency and mortality. We assessed plasma viral load in HIV-1-infected patients with pulmonary TB (HIV/TB) and non-TB symptomatic HIV-1-infected patients (HIV). HIV-1 load was higher in HIV/TB compared with HIV at higher CD4 counts (> 500/microl) (P < 0.01), but not at lower CD4 counts (< 500/microl). We also evaluated the status of HIV-1 gene expression in peripheral blood mononuclear cells (PBMC) and serum from HIV/TB and CD4-matched healthy HIV-infected patients (HIV/C) by reverse transcriptase-polymerase chain reaction over a range of CD4 (> 900/microl to < 200/microl). HIV-1 RNA in serum and PBMC correlated to one another, and both were markedly higher in HIV/TB compared with HIV/C with higher CD4 counts. Also, during a longitudinal study of anti-tuberculous chemoprophylaxis in HIV-1-infected patients, 10 subjects who developed TB had serologies before, at the time, and after the diagnosis of TB. These HIV/TB patients had an increase in viral load (average 2.5-fold) at the time of diagnosis of TB (P < 0.05). Overall, these data indicate that the transcriptional activity of HIV-1 is enhanced in HIV-1-infected patients with active TB, especially during early HIV-1 disease. As TB often is an early HIV-1 opportunistic infection, it may particularly favour early viral replication and dissemination, and therefore contribute to progression of HIV-1 disease.

AIDS-Related Opportunistic Infections↗

PubMed2001

An increase in expression of a Mycobacterium tuberculosis mycolyl transferase gene (fbpB) occurs early after infection of human monocytes.

Changes in the mRNA levels of two Mycobacterium tuberculosis genes (fbpB known as antigen 85B, and hspX known as Acr) were studied in infected human monocytes. Antigen 85B is an enzyme involved in cell wall biosynthesis and is also a major target of the immune response. Acr is a stress protein believed to be involved in the bacillary response to adverse conditions and in non-replicating persistence. During the first 24 h of intracellular infection, the intramonocyte 85B mRNA level increased 54-fold (P = 0.00001) and 14.6 times in comparison with the 16S ribosomal rRNA. In contrast, the Acr mRNA fell 14.3 times. Although monocyte cytokine production was very variable, the 24 h secretion of tumour necrosis factor (TNF)-alpha correlated with the 85B-16S RNA ratio at 24 h (r = 0.77, Pcorr < 0.01). Furthermore, the addition of exogenous TNF-alpha to cultures was associated with a twofold increase in the 85B-16S ratio and, conversely, neutralization of endogenous TNF-alpha reduced the ratio. As antigen 85B also induces TNF-alpha, the positive feedback implied by our findings suggests a previously unsuspected role for this protein in the immunopathogenesis of tuberculosis.

Acyltransferases↗

PubMed2001

Differential activation of MAP kinase signaling pathways and nuclear factor-kappaB in bronchoalveolar cells of smokers and nonsmokers.

BACKGROUND: Prolonged exposure of alveolar macrophages (AM) to components of tobacco smoke, including nicotine and aromatic hydrocarbons, may lead to alterations in activation of cellular signaling pathways. In this study, we compared the spontaneous and LPS-stimulated activation of MAP kinases and NF-kappaB in bronchoalveolar cells (BAC) from smokers and nonsmokers. MATERIAL AND METHODS: BAC, which were predominantly comprised of AM, were obtained by bronchoalveolar lavage of healthy volunteering adult smokers and nonsmokers. Nuclear and cytoplasmic extracts were prepared from cell lysates. Activation of NF-kappaB was assessed by electrophoretic mobility shift assay. Degradation of the inhibitor of NF-kappaB (IkappaB) and total MAP kinases were assessed by Western blot analysis. Activation of MAP kinases, ERK, SAPK/JNK, and p38 were assessed by immunoprecipitation of cell lysates and kinase assays. RESULTS: LPS induced the activation of NF-kappaB in a dose-dependent manner, but BAC from smokers were approximately 10 times more sensitive, and showed faster kinetics of activation of NF-kappaB than BAC from nonsmokers. All three classes of MAP kinase-ERK, SAPK, and p38-were simultaneously activated by LPS in BAC from smokers and nonsmokers. However, the individual MAP kinases exhibited differential kinetics of activation. Activation of p38 was more rapid in BAC from smokers, whereas the activation of ERK and SAPK was similar in both groups. CONCLUSION: The differences in activation of NF-kappaB and MAP kinases in BAC from smokers and nonsmokers may relate to the differences in their microenvironment in situ as affected by chronic exposure to cigarette smoke. These differences may contribute to the increased susceptibility of smokers to infections, including infection with HIV-1, and lung disease.

Adult↗

PubMed2000

Modeling HIV transfer between dendritic cells and T cells: importance of HIV phenotype, dendritic cell-T cell contact and T-cell activation.

OBJECTIVE: To study the requirements for HIV transfer between dendritic cells (DC) and CD4 T cells, using an in vitro model, combined with flow cytometry. METHODS: Immature DC and macrophages (MA) were generated from monocytes. After infection, DC or MA were cultured alone or with purified CD4 T cells. Intracellular HIV was measured, using (1) the monocyte (MO)-tropic AD8 HIV, endowed with enhanced green fluorescent protein (EGFP); and (2) intracellular staining of laboratory HIV strains and clones from primary isolates. RESULTS: (1) Clone AD8-EGFP infected DC and MA with equal efficiency, but the virus was preferentially transferred from DC to autologous T cells. (2) DC were more productively infected with R5/NSI, as compared to X4/SI, HIV, but both HIV phenotypes were easily transmitted to autologous T4 cells. (3) HIV-infected DC transferred the virus to T cells across a semi-permeable membrane, if the T cells were in contact with non-infected DC. (4) Co-culture of T cells with autologous non-infected DC induced T-cell activation. HIV-infected DC selectively increased HLA-DR on T cells and HLA-DR (+) T cells were preferential targets for HIV transfer. (5) Resting Ba-L-infected CD4 T cells were able to transmit the virus 'inversely' to co-cultured DC. CONCLUSION: HIV transfer between monocyte-derived dendritic cells and autologous CD4 T cells was directly demonstrated using flow cytometry. The transfer proceeded in both directions, depended on cellular contact and was associated with partial T-cell activation. This model, representing relevant in vivo targets of HIV, is useful to further investigate interactions between HIV, DC and T cells, without the need for primary ex vivo DC.

CD4-Positive T-Lymphocytes↗

PubMed2000

Greater diversity of HIV-1 quasispecies in HIV-infected individuals with active tuberculosis.

OBJECTIVE: A continual increase in intrapatient HIV-1 heterogeneity is thought to contribute to evasion of host immune response and eventual progression to AIDS. Tuberculosis (TB) is diagnosed both early and late during the course of HIV-1 disease and may increase diversity of HIV-1 quasispecies by activating the HIV-1 immune response and increasing HIV-1 replication. We examined whether HIV-1 heterogeneity is altered in HIV-1-infected individuals with TB. METHODS: Blood samples were obtained from 7 HIV-1-infected patients with active TB (HIV/TB patients) and 9 HIV-1-infected patients (HIV patients) in Kampala, Uganda (CD4 counts of 0-650 cells/microl and HIV loads of 700-750,000 RNA copies/ml). The C2-C3 region of the HIV-1 envelope gene (env) was amplified by nested polymerase chain reaction (PCR) from lysed peripheral blood mononuclear cells (PBMCs) of each patient, and then subject to sequencing, clonal-quasispecies analysis and heteroduplex tracking analysis (HTA). RESULTS: HTA of env DNA fragments showed increased heterogeneity in the HIV/TB individuals compared with the HIV group. Further sequence and HTA analysis on ten individual env clones for each patient showed significantly greater HIV mutation frequencies in HIV/TB patients than in HIV patients. CONCLUSION: An increase in HIV-1 heterogeneity may be associated with a TB-mediated increase in HIV-1 replication. However, a diverse HIV-1 quasispecies population in HIV/TB patients as opposed to tight quasispecies clusters in HIV patients suggests a possible dissemination of lung-derived HIV-1 isolates from the TB-affected organ.

Adult↗

PubMed2000

Pulmonary mononuclear cell responses to antigens of Mycobacterium tuberculosis in healthy household contacts of patients with active tuberculosis and healthy controls from the community.

Protective immunity against Mycobacterium tuberculosis requires CD4+ lymphocyte-mediated immune responses and IFN-gamma activity. As the primary portal of entry of M. tuberculosis is the lung, pulmonary immune responses against multiple M. tuberculosis Ags were compared between both M. tuberculosis-exposed tuberculin skin test-positive healthy household contacts (HHC) of patients with active sputum smear and culture-positive tuberculosis and tuberculin skin test-positive healthy control individuals from the community (CC). Frequencies of M. tuberculosis Ag-specific IFN-gamma-producing cells, IFN-gamma concentrations in culture supernatants, and DNA synthesis in bronchoalveolar cells (BAC) and PBMC were studied in HHC (n = 10) and CC (n = 15). Using enzyme-linked immunospot assay we found higher frequencies of IFN-gamma-producing cells with specificity to M. tuberculosis-secreted Ag 85 (Ag 85) in BAC from HHC than in BAC from CC (p < 0.022) and relative to autologous PBMC, indicating compartmentalization of Ag 85-specific cells to the lungs. Further, IFN-gamma-producing cells with specificity to components A and B of Ag 85 were specifically compartmentalized to the lungs in HHC (p < 0. 05). IFN-gamma concentrations in culture supernatants of BAC and Ag-specific DNA synthesis were low and comparable in the two subject groups. Increased immune responses to Ag 85 at the site of repeated exposure to M. tuberculosis (the lung) may represent an important component of protective immunity against M. tuberculosis. Correlates of protective immunity against M. tuberculosis are required for assessment of the efficiency of anti-tuberculous vaccines.

Acyltransferases↗

PubMed2000

Enhancement of the human T cell response to culture filtrate fractions of Mycobacterium tuberculosis by microspheres.

An improved method of assessment of the human immune response against Mycobacterium tuberculosis antigens will assist the development of new vaccines or diagnostic reagents. In this study, we have analyzed human T cell responses to culture filtrate fractions (CFF) of actively replicating M. tuberculosis strain H37Rv using peripheral blood mononuclear cells from healthy PPD skin test positive and negative individuals. Adsorption of CFF onto polystyrene microspheres, that were approximately the size of the M. tuberculosis (bead-adsorbed antigens, BAA) significantly enhanced IFN-gamma production compared to soluble antigens (SA) in PPD skin test positive individuals in an antigen-specific manner. Further, BAA induced activation of both CD4(+) and CD8(+) T cell subsets. However, CD4(+) responses in general were higher and their antigenic repertoire was wider than the CD8(+) responses. By contrast, CD8(+) responses were strongest to the lower molecular weight BAA. When CFF were chemically coupled to carboxyl modified microspheres (bead-coupled antigens, BCA), induction of IFN-gamma was similar to BAA. Enhancement of T cell responses to particulate M. tuberculosis antigens may prove useful in vaccine design strategies.

Adsorption↗