Elevated ex vivo monocyte chemotactic protein-1 (CCL2) in pulmonary as compared with extra-pulmonary tuberculosis
© Hasan et al; licensee BioMed Central Ltd. 2005
Received: 12 April 2005
Accepted: 07 July 2005
Published: 07 July 2005
Tuberculosis causes 3 million deaths annually. The most common site of tuberculosis is pulmonary however; extra-pulmonary forms of the disease also remain prevalent. Restriction of Mycobacterium tuberculosis depends on effective recruitment and subsequent activation of T lymphocytes, mononuclear and polymorphonuclear cells to the site of infection. Tumor necrosis factor (TNF)-α is essential for granuloma formation and is a potent activator of monocyte chemotactic protein (MCP-1, CCL2). CCL2 is essential for recruitment of monocytes and T cells and has been shown to play a role in protection against tuberculosis. Interleukin -8 (CXCL8) is a potent activator of neutrophils. Increased levels of CCL2, CXCL8 and TNFα are reported in tuberculosis but their significance in different forms of tuberculosis is as yet unclear. We have used an ex vivo assay to investigate differences in immune parameters in patients with either pulmonary or extra-pulmonary tuberculosis.
Serum levels of CCL2, CXCL8 and TNFα were measured in patients with pulmonary tuberculosis (N = 12), extra-pulmonary tuberculosis (N = 8) and BCG-vaccinated healthy volunteers (N = 12). Whole blood cells were stimulated with non-pathogenic Mycobacterium bovis bacille-Calmette Guerin (BCG) vaccine strain or bacterial lipopolysaccharide (LPS) and cyto/chemokines were monitored in supernatants.
Circulating serum levels of CXCL8 and TNFα were raised in all tuberculosis patients, while CCL2 levels were not. There was no difference in spontaneous cytokine secretion from whole blood cells between patients and controls. M. bovis BCG-induced ex vivo CCL2 secretion was significantly greater in pulmonary as compared with both extra-pulmonary tuberculosis patients and endemic controls. In response to LPS stimulation, patients with pulmonary tuberculosis showed increased CCL2 and TNFα responses as compared with the extra-pulmonary group. BCG-, and LPS-induced CXCL8 secretion was comparable between patients and controls.
CCL2 is activated by TNFα and is essential for recruitment of monocytes and T cells to the site of mycobacterial infection. Increased CCL2 activation in pulmonary tuberculosis may result in a stronger cellular response as compared with extra-pulmonary tuberculosis patients, and this may contribute to the localization of infection to the pulmonary site.
Tuberculosis is a major cause of morbidity and mortality worldwide, causing approximately 3 millions deaths annually . Mycobacterium tuberculosis, the causative agent of tuberculosis is a successful pathogen due to its ability to down regulate host immune responses. The primary site of infection for M. tuberculosis is the alveolar macrophage. In cases where pulmonary infection cannot be controlled the organism disseminates via blood to other sites. Pulmonary involvement is seen in the majority of tuberculosis cases however infections of extra-pulmonary sites such as lymph nodes, skeletal, abdominal and genito-urinary sites also remain common .
Local cellular responses required for restriction of infection with M. tuberculosis are fairly well understood. Granulomas which are the characteristic histopathologic lesions of tuberculosis can be formed in any infected tissue. Granulomas exhibit a characteristic mixture of macrophages and lymphocytes and the outcome of infection depends on the interplay between immune activating cytokines produced at this site. T cell interferon -gamma (IFN-γ) and macrophage activating tumor necrosis factor-alpha (TNFα) are critical for protection and play a central role in granuloma formation [3, 4]. Recent studies have also indicated an important role for chemokines in granuloma formation [5, 6].
Chemokines are small mass chemotactic cytokines produced by epithelial cells, mast cells, monocytes and neutrophils. Chemokines can be grouped into structurally different families including C-C chemokines; monocyte chemotactic protein-1 (MCP-1, CCL2), macrophage inflammatory protein-1α (MIP-1α, CCL3), MIP-1β (CCL4) and regulated-upon-activation, normally T-cell-expressed and-secreted (RANTES, CCL5) and C-X-C chemokines such as, IL-8 (CXCL8), MIG (CXCL9) and IP-10 (CXCL10). These are all activated by M. tuberculosis . CCL2 is the most potent chemoattractant and activator for monocytes and attracts CD4 and γδ T cells . CCL2 has also been shown to play a role in protection against murine tuberculosis [9–11]. CXCL8 is the most potent attractant and activating factor for neutrophils and is chemotactic for lymphocytes [12, 13]. CXCL8 is required for stimulation of a pro-inflammatory response against M. tuberculosis and its components .
Previous studies have shown that in vivo (circulating) serum levels of IFNγ, IL-10 , TNFα , CXCL8 and IL-6  are raised in pulmonary tuberculosis. Circulating levels of chemokines CXCL8, CCL2 and RANTES are raised in bronchoalveolar lavage fluid (BALF) and alveolar macrophages from pulmonary tuberculosis patients [18, 19]. Increased CXCL8 and CCL2 activation is also observed in patients with tuberculous pleurisy  and meningitis [21, 22]. In addition, the expression levels of cytokines and chemokines have been correlated with disease severity  and with subsequent recovery after treatment [23, 24].
We have focused on immune responses in newly diagnosed untreated tuberculosis patients with either pulmonary, or extra-pulmonary disease. We observed that systemic levels of CXCL8 and TNFα were raised in all patients while CCL2 was not. Using an ex vivo whole blood assay we observed differential Mycobacterium-induced and LPS stimulated responses between patients with pulmonary and extra-pulmonary tuberculosis. Mycobacterium-induced CCL2 and TNFα, and LPS-induced TNFα responses were greater in pulmonary as compared with extra-pulmonary tuberculosis. However, both Mycobacterium-, and LPS-induced CXCL8 responses were comparable between patient groups.
Hematological characteristics of study subjects
Pul-TB, N = 10 Median (range)
EPul-TB, N = 8 Median (range)
Controls, N = 12 Median (range)
25 (15 – 50)
32 (15 – 58)
TLC (10 xE9/L)
9.8 (7 – 22.2)
9.4 (6.4 – 16.3)
7.2 (3 – 9)
64 (38 – 87)
70 (60 – 90
56 (38.1 – 70.6)
6.7 (3.6 – 9.2)
7.4 (1.7 – 11.4)
7.2 (5.8 – 9.4)
3 / 8
%PPD+ (No. tested)
LPS-induced CCL2, CXCL8 and TNFα secretion in TB patients
Chemo/cytokines pg/ml Median (range)
EC (N = 12)
* 3 1153 (0–1489)
Pul (N = 10)
* 1 1218 (765–2254)
* 3,4 2154 (1244–4852)
* 2 3398 (1643–7012)
E-Pul (N = 8)
* 1 33 (0–818)
* 4 577 (0–2180)
* 2 32 (0–1194)
Serum CCL2, CXCL8 and TNFα in tuberculosis patients
BCG-, and LPS -induced CCL2, CXCL8 and TNFα
CCL2, CXCL8 and TNFα secretion in whole blood cells from tuberculosis patients
Baseline (spontaneous) levels of CCL2, CXCL8 and TNFα were determined in Pul-TB, EPul-TB and control groups. Chemokine activity was measured in supernatants of un-stimulated whole blood cells after 18 h and 48 h of ex vivo culture. At 18 h, increased levels of CCL2 were observed in the Pul-TB group; 438 pg/ml (median) (range, 0–3000 pg/ml) as compared with EPul-TB; 35 pg/ml (0–774 pg/ml) and controls; 42 pg/ml (0–102 pg/ml). Spontaneous secretion of CXCL8 after 18 h was : Pul-TB; 284 pg/ml (15–1927 pg/ml), EPul-TB; 681 pg/ml (1–2076 pg/ml) and controls; 121 pg/ml (8–2546 pg/ml). Spontaneous TNFα secretion at 18 h was: Pul-TB; 5 pg/ml (0–55 pg/ml), E-Pul-TB; 1 pg/ml (0–585 pg/ml) and controls; 25 pg/ml (0–102 pg/ml). There were no significant differences between groups in their baseline levels of CCL2, CXCL8 or TNFα (P > 0.05). Spontaneous levels of cytokines measured after 48 h (data not shown) of in vitro culture showed a similar trend as observed at 18 h, with no difference between groups.
We subsequently investigated LPS-induced CCL2, CXCL8 and TNFα in tuberculosis patients. Table 2 illustrates chemokine activity measured at 18 and 48 h post LPS stimulation. Spontaneous chemokine secretion (indicated above) have been subtracted from the values indicated in the table. LPS-induced CCL2 activation in Pul-TB was significantly greater than in EPul-TB at 18 h (*1, P = 0.01) and at 48 h (*2, P = 0.02) post-stimulation. LPS-induced CXCL8 secretion was comparable between patients and endemic controls. At 18 h, TNFα was significantly greater in Pul-TB as compared with EPul-TB (*4, P = 0.003) and also as compared with controls (*3, P = 0.003), whilst no difference was observed between these groups at 48 h.
We have used an ex vivo whole blood assay to study differences in immune parameters in pulmonary and extra-pulmonary tuberculosis. We observed that BCG-induced CCL2 responses in pulmonary tuberculosis were greater as compared to both extra-pulmonary tuberculosis and control groups. LPS stimulated CCL2 and TNFα responses were also raised in pulmonary tuberculosis as compared with extra-pulmonary tuberculosis patients.
We included both PPD skin test positive and negative individuals to be representative of our healthy endemic population, where a large proportion of BCG vaccinated individuals remain non-reactive to the PPD skin test antigen . Our tuberculosis patient group was small because of stringent selection criteria. We excluded most of those patients who had received some form of anti-tuberculous treatment for any length of time. Due to poor therapeutic practices in Pakistan the majority of patients presenting to a tertiary care center such as AKUH have received variable course anti-tuberculous therapy . There were three times as many female than male patients in our study and this ratio is representative of female preponderance in the disease pattern in Pakistan . In congruence with previous studies, neutrophils and monocyte counts were not significantly altered in patient groups . However, erythrocyte sedimentation was significantly higher in tuberculosis patients, reflective of active infection . Two extra-pulmonary tuberculosis patients (abdominal and lymphnode respectively) showed lung involvement on chest X-ray. These were grouped based on their predominant extra-pulmonary disease site and found that their responses correlated with others in the group.
The raised circulating levels of CXCL8 we observe in tuberculosis patients correlate with previous reports [16, 17]. Increased CXCL8 has been associated with increased neutrophils in broncho-alveolar lavage  and pleural fluid . However, we did not find increased neutrophils or monocytes in peripheral circulation of our patients. We observed raised TNFα in sera of tuberculosis patients. This is contrast to reports by Juffermans et al. who found that TNFα was not raised in sera of tuberculosis patients , while additional reports by Olobo et al. indicate that serum TNFα is increased in healthy contacts . We did not observe any increase in circulating CCL2, correlating with reports by Lee et al.  who compared sera from tuberculosis patients with healthy tuberculin reactive controls from a disease endemic region. This was in contrast with Juffermans et al. who observed raised CCL2 in sera of tuberculosis patients as compared with healthy individuals from a non-endemic region .
Ex vivo stimulation of whole blood leucocytes provides useful information on control of cytokine secretion, since it utilizes the host environment . Whole blood assays have been shown to provide useful insight into the immunopathology of tuberculosis infection . The time course profiles of CCL2, CXCL8 and TNFα secretion we observed in response to BCG and LPS corresponded to previous reports of Mycobacterium and LPS induced activation of purified monocytes and adherent cells [19, 35, 36]. Further, after LPS stimulation we observed greater cytokine activation than after mycobacterial stimulation as has been shown in the case of cytokines such as CXCL8 . Therefore the data we obtained using our whole blood assay correlated with patterns observed using purified subsets of cells.
Increased CCL2 in pulmonary tuberculosis may be related to localization of infection to the lung and may subsequently prevent disease dissemination. We observed raised CCL2 in pulmonary tuberculosis compared with controls in response to BCG stimulation. Raised CCL2 activation in tuberculosis correlates with previous studies [19, 32, 38]. However, this contrasts with reports by Lee et al. who did not observe any increase in CCL2 secreted by adherent cells from pulmonary tuberculosis patients as compared with healthy tuberculin reactors – in response to PPD or M. tuberculosis 30 kD antigen . One difference as compared to our study was that Lee et al. used healthy controls with a PPD skin test induration > 15 mm, while our control group comprised of either PPD negative or PPD positive individuals with induration > 10 mm. In addition, the use of live Mycobacteria and unprocessed whole blood is likely to give more physiologically relevant results for in vivo chemokine and cytokine activation as compared with recombinant antigen or subunit preparations. We also observed greater CCL2 activation in pulmonary tuberculosis as compared with extra-pulmonary disease in response to both BCG and LPS stimulation.
LPS-induced CXCL8 was not raised in whole blood cells from patients and this was paradoxical with increased levels in sera of these patients. Differences between in vivo (serum and plasma) and in vitro (PBMC-induced cytokine) activation have been shown previously . Previously, we have shown increased spontaneous CXCL8 in disseminated mycobacterial (leprosy) infections while inducible CXCL8 was not raised in patients . Therefore, increased levels of CXCL8 in sera may be indicative of pathology in these patients and may not contribute to the effective recruitment of cells.
TNFα levels were raised in pulmonary as compared with both extra-pulmonary tuberculosis and controls in response to LPS but not BCG stimulation. This difference in TNFα levels was evident at the earlier (18 h) but not later time interval. Probably, due to the reduced time course profile of TNFα by 48 h. Lack of difference in TNFα in response to BCG between groups, may also be due to reduced overall levels induced by mycobacterium as compared with the LPS.
Macrophages and other polymorphonuclear cells play essential roles in initiation and maintenance of immune responses to M. tuberculosis. Pro-inflammatory TNFα, CCL2 and CXCL8 are important in maintaining a balance between recruitment of other macrophages and also T cells to restrict infection. CCL2 contributes to anti-mycobacterial inflammatory response by attracting monocytes and T lymphocytes. Raised CCL2 in pulmonary tuberculosis may lead to greater monocyte mediated immunity. Reduced CCL2 concomitant with lowered TNFα in extra-pulmonary tuberculosis may lead to lowered protective cellular responses and increased dissemination in these patients.
Subject selection and diagnosis
Patients were recruited from the Aga Khan University (AKUH) and Masoomeen Hospitals in Karachi. Ethical Clearance was obtained from the AKUH Human Subjects Protection and Ethical Review Committee and samples were taken from patients with informed consent. All study subjects were examined and investigated by infectious diseases consultants. Patients with significant co-morbid conditions including diabetes mellitus, chronic renal failure, chronic liver disease, those on high dose corticosteroid therapy and those with HIV/AIDS were excluded from this analysis. All patients were untreated except for two who had been on anti-tuberculous therapy for 2 months each due to delays in diagnostic confirmation of extra-pulmonary tuberculosis. Patients were diagnosed by clinical examination, chest X-ray, sputum M. tuberculosis microscopy and culture. Chest X-rays were evaluated by one of the consulting physicians using the classification of the National Tuberculosis Association of the USA into minimal, moderate and advanced lung tissue involvement . Microscopy was performed using Ziehl-Neelsen staining. Cultures were done by means of a set of Lowenstein Jensen slants with and without glycerol. Purified protein derivative (PPD) skin test was carried out on each study subject. PPD skin test negative were those with induration < 10 mm, with PPD positive with induration = 10 mm. Hematological parameters for all subjects were noted on the date of enrollment and shown in Table 1. The pulmonary tuberculosis (Pul-TB) group comprised of 10 patients (3 males and 7 females) with moderate disease and no other site involved except the lung. The extra-pulmonary tuberculosis (EPul-TB) group comprised of 8 patients (2 males and 6 females) with tuberculosis in the following sites; lymph nodes (N = 3), pericardial effusion (N = 2), meningitis (N = 1), abdomen (N = 2). Of the EPul-TB patients, 6/8 were confirmed on M. tuberculosis smear/culture and/or radiology, while 2/8 were diagnosed on the basis of clinical presentation and a favorable response to anti-tuberculosis drugs. Two of the EPul-TB patients also showed pulmonary involvement on Chest X-ray. Twelve BCG-vaccinated healthy endemic controls (EC) (9 males and 3 females) who were staff at the AKUH were also included in the study. PPD+ volunteers had normal chest X-Ray and no clinical evidence of active disease.
Mycobacterium bovis BCG (Montreal vaccine strain) was grown to logarithmic phase in 7H9 Middlebrook medium with supplements (DIFCO Laboratories, MI, USA). Mycobacteria were frozen in growth medium containing 20 % glycerol and stored at -70°C in single use aliquots for the assay as described previously . Mycobacterial viability was confirmed prior to assays by fluorescent staining  and by colony counts on Middlebrook 7H11 agar.
Whole blood assays
Venous blood was diluted 1: 10 in RPMI-1640 medium each well containing 106 whole blood cells was set up as per protocol . Freshly thawed aliquots of BCG were washed in PBS and diluted to infect cells as described previously . Each was stimulated with either E. coli lipopolysaccharide (LPS) (Sigma, USA) 0.1 μg/ml or mycobacteria at 2 × 105 CFU/ml (at a ratio of 0.2 bacteria per cell). Supernatants were collected at 0, 1, 6, 18, 48 and 120 h (5 days) post infection for chemokine measurement, spun to collect cellular debris and stored at -70 C until tested. BCG innoculum was tested for LPS contamination using the E-Toxate Kit (Sigma, USA).
ELISA reagents for CCL2, CXCL8 and TNFα were from R&D Systems (USA). Assays were carried out according to the manufacturer's recommendation and as reported previously . The lower limit of detection for CCL2 was 7.8 pg/ml, and 3.9 pg/ml for TNFα and CXCL8.
Data is expressed as Mean (SD) or Median as described in figures. Statistical analysis was carried out using Mann-Whitney U test for Pair-wise analysis of groups using the SPSS package, USA and also ANOVA analysis.
List of abbreviations used
bacille-Calmette Guerin vaccine strain
tumor necrosis factor alpha
C-C chemokine ligand 2
C-X-C chemokine ligand 8.
This study was supported by a Seed Money Grant, The Aga Khan University, Karachi, Pakistan. Thanks for help with patient recruitment to Dr. Ghaffar Dawood, Masoomeen Hospital, Karachi, Pakistan.
- WHO: Global Tuberculosis Control. 2003, 99-101.Google Scholar
- Fanning A: Tuberculosis: 6. Extrapulmonary disease. C M A J. 1999, 160: 1597-1603.Google Scholar
- Smith S, Liggitt D, Jeromsky E, Tan X, Skerrett SJ, Wilson CB: A local role for tumor necrosis factor alpha in the pulmonary inflammatory response to Mycobacterium tuberculosis infection. Infect Immun. 2002, 70: 2082-2089. 10.1128/IAI.70.4.2082-2089.2002.PubMed CentralView ArticlePubMedGoogle Scholar
- Kindler V, Sappino AP, Grau GE, Piguet PF, Via LE, Vassalli P: The inducing role of tumor necrosis factor in the development of bactericidal granulomas during BCG infection. Cell. 1989, 56: 731-740. 10.1016/0092-8674(89)90676-4.View ArticlePubMedGoogle Scholar
- Qiu B, Frait KA, Reich F, Komuniecki E, Chensue SW: Chemokine expression dynamics in mycobacterial (Type-1) and schistosomal (Type-2) antigen-elicited pulmonary granuloma formation. Am J Pathol. 2001, 158: 1503-1515.PubMed CentralView ArticlePubMedGoogle Scholar
- Roach DR, Bean AGD, Demangel C, France MP, Briscoe H, Britton WJ: TNF regulates chemokine induction essential for cell recruitment, granuloma formation, and clearance of mycobacterial infection. J Immunol. 2002, 168: 4620-4627.View ArticlePubMedGoogle Scholar
- Algood HMS, Chan J, Flynn JL: Chemokines and tuberculosis. Cytokine-Growth-Factor-Rev. 2003, 14: 467-477. 10.1016/S1359-6101(03)00054-6.View ArticlePubMedGoogle Scholar
- Penido C, Vieira-de-Abreu A, Bozza MT, Castro-Faria-Neto HC, Bozza PT: Role of monocyte chemotactic protein-1/CC chemokine ligand 2 on gd T lymphocyte trafficking during inflammation induced by lipopolysaccharide of Mycobacterium bovis bacille Calmette-Guerin. J Immunol. 2003, 171: 6788-6794.View ArticlePubMedGoogle Scholar
- Kipnis A, Basaraba RJ, Orme IM, Cooper AM: Role of chemokine ligand 2 in the protective response to early murine pulmonary tuberculosis. Immunology. 2003, 109: 547-551. 10.1046/j.1365-2567.2003.01680.x.PubMed CentralView ArticlePubMedGoogle Scholar
- Scott HM, Flynn JL: Mycobacterium tuberculosis in chemokine receptor 2-deficient mice: Influence of dose on disease progression. Infect Immun. 2002, 70: 5946-5954. 10.1128/IAI.70.11.5946-5954.2002.PubMed CentralView ArticlePubMedGoogle Scholar
- Peters W, Scott HM, Chambers HF, Flynn JL, Charo IF, Ernst JD: Chemokine receptor 2 serves an early and essential role in resistance to Mycobacterium tuberculosis. Proc-Natl-Acad-Sci-USA. 2001, 98: 7958-7963. 10.1073/pnas.131207398.PubMed CentralView ArticlePubMedGoogle Scholar
- Moser B, Wolf M, Walz A, Loetscher P: Chemokines: multiple levels of leukocyte migration control. Trends Immunol. 2004, 25: 75-84. 10.1016/j.it.2003.12.005.View ArticlePubMedGoogle Scholar
- Park JS, Kim YS, Jee YK, Myong NH, Lee KY: Interleukin-8 production in tuberculous pleurisy: role of mesothelial cells stimulated by cytokine network involving tumour necrosis factor-a and interleukin-1b. Scand J Immunol. 2003, 57: 463-469. 10.1046/j.1365-3083.2003.01201.x.View ArticlePubMedGoogle Scholar
- Wilkinson PC, Newman I: Identification of IL-8 as locomotor attractant for activated human lymphocytes in mononuclear cell cultures with anti-CD3 or purified protein derivative of Mycobacterium tuberculosis. J Immunol. 1992, 149: 2689-2694.PubMedGoogle Scholar
- Dlugovitzky D, Bay ML, Rateni L, Fiorenza G, Vietti L, Farroni MA: Influence of disease severity on nitrite and cytokine production by peripheral blood mononuclear cells (PBMC) from patients with pulmonary tuberculosis (TB). Clin Exp Immunol. 2000, 122: 343-349. 10.1046/j.1365-2249.2000.01394.x.PubMed CentralView ArticlePubMedGoogle Scholar
- Juffermans NP, Verbon A, Deventer SJH, Deutekom H, Belisle JT, Ellis ME, Speelman P, van der Poll T: Elevated chemokine concentrations in sera of human immunodeficiency virus (HIV)-seropositive and HIV-seronegative patients with tuberculosis: a possible role for mycobacterial lipoarabinomannan. Infect Immun. 1999, 67: 4295-4297.PubMed CentralPubMedGoogle Scholar
- Friedland JS, Hartley JC, Hartley CG, Shattock RJ, Griffin GE: Inhibition of ex vivo proinflammatory cytokine secretion in fatal Mycobacterium tuberculosis infection. Clin Exp Immunol. 1995, 100: 233-238.PubMed CentralView ArticlePubMedGoogle Scholar
- Kurashima K, Mukaida N, Fujimura M, Yssui M, Nakazumi Y, Matusda T, Matsushima K: Elevated chemokine levels in bronchalveolar lavage fluid of tuberculosis patients. Am J Respir Crit Care Med. 1997, 155: 1474-1477.View ArticlePubMedGoogle Scholar
- Sadek MI, Sada E, Toosi Z, Schwander SK, Rich EA: Chemokines induced by infection of mononuclear phagocytes with mycobacteria and present in lung alveoli during active pulmonary tuberculosis. Am J Respir Cell Mol Biol. 1998, 19: 513-21.View ArticlePubMedGoogle Scholar
- Fietta AM, Morosini M, Meloni F, Bianco AM, Pozzi E: Pharmacological analysis of signal transduction pathways required for Mycobacterium tuberculosis-induced IL-8 and MCP-1 production in human peripheral monocytes. Cytokine. 2002, 19: 242-249. 10.1016/S1043-4666(02)91968-X.View ArticlePubMedGoogle Scholar
- Mastroianni CM, Lancella L, Mengoni F, Lichtner M, Santopadre P, Dagostino C, Ticca F, Vullo V: Chemokine profiles in the cerebrospinal fluid (CSF) during the course of pyogenic and tuberculous meningitis. Clin Exp Immunol. 1998, 114: 210-214. 10.1046/j.1365-2249.1998.00698.x.PubMed CentralView ArticlePubMedGoogle Scholar
- Thwaites GE, Simmons CP, Quyen NTH, Chau TTH, Mai PP, Dung NT, Phu NH, White NP, Hien TT: Pathophysiology and prognosis in Vietnamese adults with tuberculous meningitis. J Infect Dis. 2003, 188: 1105-1115. 10.1086/378642.View ArticlePubMedGoogle Scholar
- Verbon A, Juffermans NP, Deventer SJH, Speelman P, Deutekom H, van der Poll T: Serum concentrations of cytokine in patients with active tuberculosis (TB) and after treatment. Clin Exp Immunol. 1999, 115: 110-113. 10.1046/j.1365-2249.1999.00783.x.PubMed CentralView ArticlePubMedGoogle Scholar
- Riberio-Rodrifues R, Co TR, Johnson JL, Riberio F, Palaci M, Sa RT, Maciel EL, Lima FEP, Dettoni V, Toosi Z, Boom WH, Dietze R, Ellner J, Hirsch CS: Sputum cytokine levels in patients with pulmonary tuberculosis as early markers of mycobacterial clearance. Clin Diagn Lab Immunol. 2002, 9: 818-823. 10.1128/CDLI.9.4.818-823.2002.Google Scholar
- Menzies R, Vissandjee B: Effect of bacille Calmette-Guerin vaccination on tuberculin reactivity. Am Rev Resp Dis. 1992, 145: 621-625.View ArticlePubMedGoogle Scholar
- Khan J, Malik A, Hussain H, Ali NK, Akbani F, Hussain SJ, Kazi GN, Hussain SF: Tuberculosis diagnosis and treatment practices of private physicians in Karachi, Pakistan. East Mediterr Health J. 2003, 9: 769-775.PubMedGoogle Scholar
- Hussain SF, Irfan M, Abbasi M, Anwer SS, Davidson S, Haqqee R, Khan JA, Islam M: Clinical characteristics of 110 miliary tuberculosis patients from a low HIV prevalence country. Int J Tuberc Lung Dis. 2004, 8: 493-499.PubMedGoogle Scholar
- Hussain R, Hasan R, Khurshid M, Sturm AW, Ellner JJ, Dawood G: Pulmonary tuberculosis in a BCG vaccinated area: Relationship of disease severity with immunological and hematological parameters and drug resistance patterns. Southeast Asian J Trop Med Public Health. 1996, 27: 1-6.Google Scholar
- Barnes PF, Cave MD: Molecular epidemiology of tuberculosis. New Engl J Med. 2003, 349: 1149-1156. 10.1056/NEJMra021964.View ArticlePubMedGoogle Scholar
- Juffermans NP, Verbon A, vn Deventer SJH, van Deutekom H, Speelman P, van der Poll T: Tumor necrosis factor and interleukin-1 inhibitors as markers of disease activity of tuberculosis. Am J Resp Crit Care Med. 1998, 157: 1328-1331.View ArticlePubMedGoogle Scholar
- Olobo JO, Geletu M, Demissie A, Eguale T, Hiwot K, Aderaye G, Britton S: Circulating TNF-α, TNF-β and IL-10 in tuberculosis patients and healthy contacts. Scan J Immunol. 2001, 53: 85-91. 10.1046/j.1365-3083.2001.00844.x.View ArticleGoogle Scholar
- Lee JS, Song CH, Lim JH, Kim HJ, Park JK, Paik TH, Jo EK: Monocyte chemotactic protein-1 production in patients with active pulmonary tuberculosis and tuberculous pleurisy. Inflamm res. 2003, 52: 297-304.PubMedGoogle Scholar
- DeGroote D, Zangerle PF, Gevaert Y: Direct stimulation of cytokines (IL-1β, TNF-α, IL-6, IL-2, IFN-γ and GM-CSF) in whole blood. Cytokine. 1991, 4: 239-48. 10.1016/1043-4666(92)90062-V.View ArticleGoogle Scholar
- Hussain R, Kaleem A, Shahid F, Dojki M, Jamil B, Mehmood M, Dawood G, Dockrell HM: Cytokine profiles using whole-blood assays can discriminate between tuberculosis patients and healthy endemic controls in a BCG-vaccinated population. J Immunol Methods. 2002, 264: 95-108. 10.1016/S0022-1759(02)00092-3.View ArticlePubMedGoogle Scholar
- Kasahara K, Tobe T, Tomita M, Mukaida N, Shao-Bo S, Matsushima K, Yoshida.T, Sugihara S, Kobayashi K: Selective expression of monocyte chemotactic and activating factor / monocyte chemotactic protein 1 in human blood monocytes by Mycobacterium tuberculosis. J Infect Dis. 1994, 170: 1238-1247.View ArticlePubMedGoogle Scholar
- Faldt J, Dahlgren C, Ridell M: Difference in neutrophil cytokine production induced by pathogenic and non-pathogenic mycobacteria. Apmis. 2002, 110: 593-600. 10.1034/j.1600-0463.2002.1100901.x.View ArticlePubMedGoogle Scholar
- Kasahara K, Sato I, Ogura K, Takeuchi H, Kobayashi K, Adachi M: Expression of chemokines and induction of rapid cell death in human blood neutrophils by Mycobacterium tuberculosis. J Infect Dis. 1998, 178: 127-137.View ArticlePubMedGoogle Scholar
- Lin Y, Gong J, Zhang M, Xue W, Barnes PF: Production of monocyte chemoattractant protein 1 in tuberculosis patients. Infect Immun. 1998, 66: 2319-2322.PubMed CentralPubMedGoogle Scholar
- Vankayalapati R, Wizel B, Weis SE, Klucar P, Shams H, Samten B, Barnes PF: Serum cytokine concentrations do not parallel Mycobacterium tuberculosis -induced cytokine production in patients with tuberculosis. Clin Infect Dis. 2003, 36: 24-28. 10.1086/344903.View ArticlePubMedGoogle Scholar
- Hasan Z, Mahmood A, Zafar S, Khan AA, Hussain R: Leprosy patients with lepromatous disease have an up-regulated IL-8 response that is unlinked to TNFα responses. Int J Lepr other Mycobact Dis. 2004, 72: 35-44. 10.1489/1544-581X(2004)072<0035:LPWLDH>2.0.CO;2.View ArticlePubMedGoogle Scholar
- Crofton J: Clinical features of tuberculosis. Crofton and Douglas Respiratory Diseases. 1990, London, Blackwell Scientific, 395-421.Google Scholar
- Kvach JT, Veras JR: A fluorescent staining procedure for determining the viability of mycobacterial cells. Int J Lepr other Mycobact Dis. 1982, 50: 183-192.PubMedGoogle Scholar
- Hasan Z, Shah BH, Mahmood A, Young DB, Hussain R: The effect of mycobacterial virulence and viability on MAP kinase signaling and TNFα production by human monocytes. Tuberculosis. 2003, 83: 299-309. 10.1016/S1472-9792(03)00003-9.View ArticlePubMedGoogle Scholar
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