The immunology of mycobacterial diseases

P2X7 1513A/C loss-of-function polymorphism and active tuberculosis disease in a cohort of Egyptian population: a pilot study

Background

Tuberculosis (TB) is a multifactorial disease, and increasing evidence shows that genetic variants in regulating genes of immune response confer susceptibility to active TB at the individual level. We aimed to identify the contribution of P2X7 receptor 1513A/C genetic polymorphisms to different clinical forms of active tuberculosis in a cohort of Egyptian population.

Methods

A case–control study that enrolled 25 newly diagnosed pulmonary TB (PTB) patients by positive sputum for AFB or positive culture, 25 extrapulmonary TB (EPTB) diagnosed by pathological/bacteriological/immunological studies and 25 healthy controls. A blood sample was taken before starting of therapy for P2X7 1513A/C polymorphism genotyping using PCR-restriction fragment length polymorphism.

Results

Fifty-two percent of the participants were in the third decade with equal gender distribution. P2X7 receptor 1513AA (homozygote wild), AC (heterozygote) and CC (homozygote mutant) genotypes were identified. AC and CC genotypes distribution were significantly more frequent in the active TB cases (either PTB or EPTB) rather than controls (p < 0.05). Further, P2X7 1513A/C genotypes’ distribution did not associate with old TB or gender (p > 0.05), but significantly associated with history of smoking (x2 trend analysis p = 0.036).

Conclusions

There is positive association between P2X7 receptor 1513A/C polymorphism and active tuberculosis in the Egyptians.

Value of serum cytokine biomarkers TNF-α, IL-4, sIL-2R and IFN-γ for use in monitoring bacterial load and anti-tuberculosis treatment progress

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Serum cytokine levels may correlate with tuberculosis patient disease status.

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Serum TNF-α level may be a useful biomarker for predicting bacillar burden.

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Serum TNF-α and IFN-γ levels may reliably monitor anti-TB treatment progress.

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Serum IL-4 level had no value while serum IL-2R level value awaits further study.

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Cytokine biomarkers are useful biomarkers in clinical TB patient care settings.

Tuberculosis (TB) patient serum cytokine levels may be predictive of anti-tuberculosis treatment progress. Here, serum levels of cytokines TNF-α, IL-4, sIL-2R and IFN-γ were measured then correlated to clinical TB manifestations, bacterial burden, chest imaging findings and clinical course. Study subjects included 67 newly diagnosed pulmonary TB (PTB) patients with active disease admitted to Beijing Chest Hospital for anti-TB chemotherapeutic treatment. Blood was drawn at 0 months (pre-treatment), 1–2 months (at any time between 1 and 2 month) and after 6 months completion of treatment and serum TNF-α, IL-4, sIL-2R and IFN-γ levels were measured in duplicate using enzyme-linked immunosorbent assays (ELISAs). Correlation analysis was conducted to evaluate sensitivity and specificity of cytokine levels as predictors of disease activity and treatment progress. The results indicated that the pre-treatment serum TNF-α level of the smear-negative group was lower than that of the smear 1+ group, while serum TNF-α after 6 months completion of treatment and IFN-γ levels at 1–2 months and after 6 months completion of treatment were significantly lower, respectively, than at 0 months (before treatment) (P < 0.05). Using a cut-off value of 845 pg/ml, serum TNF-α level was predictive of treatment progress, with a sensitivity of 51%, specificity of 60% and AUC of 0.594 (P = 0.013). Meanwhile, using a cut-off value of 393 pg/ml, serum IFN-γ provided superior monitoring efficacy, with a sensitivity of 60%, specificity of 64% and AUC of 0.651 (P = 0.017). In conclusion, both serum TNF-α and IFN-γ levels might be useful biomarkers for monitoring treatment progress.

Serum Inflammation Markers in Tuberculosis

Tuberculosis remains one of the leading infectious cause of death in the world. The goals of screening are to detect active tuberculosis early enough and to identify individuals eligible for preventive therapy to reduce a po tential co-infection by tuberculosis. Plasma/serum screening for selected potential biomarkers could represent a suitable method of tuberculosis diagnosis and treatment outcome. Furthermore, monitoring of tuberculosis treatment is crucial to clinical decision-making and besides the plasmatic concentration of administered antituberculosis drugs, the biomarkers appear to play a significant role in the estimation of the real therapeutical impact.

The current standard remains focused on culture conversion, especially two-month culture status, which has a relatively low sensitivity. Identification of non-sputum-based biomarkers of the treatment respond would be beneficial for individual monitoring of tuberculosis patients.

This mini-review describes several serological/plasmatic markers that can be analyzed by simple immunoassays as ELISA method, e.g. C-reactive protein, soluble intercellular adhesion molecule-1, soluble urokinase plasminogen activator receptor, soluble lymphocyte activation gene-3, granzyme B and soluble tumor necrosis factor receptor one and two as reliable enough as an indicator of successful treatment of tuberculosis.

Non-pigmented rapidly growing mycobacteria smooth and rough colony phenotypes pathogenicity evaluated using in vitro and experimental models

Non-pigmented rapidly growing mycobacteria (NPRGM) are widely distributed in water, soil and animals. It has been observed an increasing importance of NPRGM related-infections, particularly due to the high antimicrobial resistance. NPRGM have rough and smooth colony phenotypes, and several studies have showed that rough colony variants are more virulent than smooth ones. However, other studies have failed to validate this observation. In this study, we have performed two models, invitro and in vivo, in order to assess the different pathogenicity of these two phenotypes. We used collection and clinical strains of Mycobacteriumabscessus, Mycobacterium fortuitum and Mycobacteriumchelonae. On the invitro model (macrophages), phagocytosis was higher for M. abscessus and M. fortuitum rough colony variant strains when compared to smooth colony variants. However, we did not find differences with colonial variants of M. chelonae. Survival of Galleriamellonella larvae in the experimental model was lower for M. abscessus and M. fortuitum rough colony variants when compared with larvae infected with smooth colony variants. We did not find differences in larvae infected with M. chelonae.Results of our in vivo study correlated well with the experimental model. This fact could have implications on the interpretation of the clinical significance of the NPRGM isolate colonial variants.

Tuberculosis: Current Status, Diagnosis, Treatment and Development of Novel Vaccines

Tuberculosis (TB) is an infectious disease that mainly affects the lungs and spreads to other organs of the body through the haematogenous route. It is one of the ten major causes of mortality worldwide. India has the highest incidence of new- and multidrug-resistant (MDR) - TB cases in the world. Bacille Calmette-Guerin (BCG) is the vaccine commonly available against TB. BCG does offer some protection against serious forms of TB in childhood but its protective effect wanes with age. Many new innovative strategies are being trailed for the development of effective and potent vaccines like mucosal- and epitope-based vaccines, which may replace BCG or boost BCG responses. The use of nanotechnology for diagnosis and treatment of TB is also in the pipeline along with many other vaccines, which are under clinical trials. Further, in-silico models were developed for finding new drug targets and designing drugs against Mycobacterium tuberculosis (Mtb). These models offer the benefit of computational experiments which are easy, inexpensive and give quick results. This review will focus on the available treatments and new approaches to develop potent vaccines for the treatment of TB.

Down regulation of RANTES in pleural site is associated with inhibition of antigen specific response in tuberculosis

Tuberculosis is the most common infectious reason for death and a major cause of pleural effusion globally. To understand the role of chemokines in trafficking of cells during TB pleurisy, we studied the responses to MTB, Ag85A in cells from pleural fluids and peripheral blood. Patients with TB pleural effusions, malignant effusions and asymptomatic healthy controls were enrolled. High expression (p < 0.05) of IP-10, MCP-1, MIG, IL-8, IFN-γ and IL-23 were observed in pleural fluids of TB patients compared to their plasma where expression of RANTES was significantly higher (p < 0.05). On specific stimulation of PFMCs with Ag85A, expression of RANTES was significantly lower in TB compared to NTB patients. We also observed increased expression of T regs and PD1 on CD8+T cells in PFMC of TB patients. Though some of the inflammatory chemokine/cytokines were up-regulated in pleura of TB patients, antigenic stimulation failed to induce them indicating poor antigenic responses at the site. Low expression of RANTES might be a reason for decreased trafficking of cells to the site and dissemination of infection into pleural site. The pattern of RANTES expression in pleural fluid vs serum is interesting. The observations necessitate further studies to investigate the levels of RANTES for its potential biological relevance in TB immunity and its use as a biomarker for diagnosis of pleural TB.

Nitric Oxide in the Pathogenesis and Treatment of Tuberculosis

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is globally known as one of the most important human pathogens. Mtb is estimated to infect nearly one third of the world's population with many subjects having a latent infection. Thus, from an estimated 2 billion people infected with Mtb, less than 10% may develop symptomatic TB. This indicates that the host immune system may constrain pathogen replication in most infected individuals. On entering the lungs of the host, Mtb initially encounters resident alveolar macrophages which can engulf and subsequently eliminate intracellular microbes via a plethora of bactericidal mechanisms including the generation of free radicals such as reactive oxygen and nitrogen species. Nitric oxide (NO), a key anti-mycobacterial molecule, is detected in the exhaled breath of patients infected with Mtb. Recent knowledge regarding the regulatory role of NO in airway function and Mtb proliferation paves the way of exploiting the beneficial effects of this molecule for the treatment of airway diseases. Here, we discuss the importance of NO in the pathogenesis of TB, the diagnostic use of exhaled and urinary NO in Mtb infection and the potential of NO-based treatments.

Mechanisms of Granulomatous Lung Disease from Inhaled Beryllium: The Role of Antigenicity in Granuloma Formation

Granulomatous lung disease is a debilitating and sometimes fatal condition encountered in humans, for which the cellular and molecular mechanisms are poorly understood. Two patterns of granulomatous lung disease are recognized; foreign-body reactions and immune-mediated granulomas. Beryllium inhalation by humans results, in a small number of exposed individuals, in a chronic, granulomatous, immune-mediated pulmonary disease (chronic beryllium lung disease, CBD). Animal models used to study CBD have demonstrated significant species differences in the pathologic response to beryllium. While rats exposed to beryllium appear to develop a chronic, foreign-body response within the lung, dogs so exposed develop beryllium-specific immune responses within the lung and blood, accompanied by immune granulomas within the lung. At the heart of this difference appears to be the ability of the dog, but not the rat, to immunologically recognize the antigenicity of beryllium. This important difference further underscores the need to understand the mechanistic differences among similar disease syndromes, particularly if therapeutic regimens are to be used.

Strains of Mycobacterium tuberculosis differ in affinity for human osteoblasts and alveolar cells in vitro

Although the lung is the primary site of infection of tuberculosis, Mycobacterium tuberculosis is capable of causing infection at other sites. In 5–10 % such extra-pulmonary tuberculosis is located in bone tissue of the spine. It is unknown whether host or microbial factors are responsible for the site where extra-pulmonary tuberculosis manifests itself. One MDR isolate belonging to strain F28, one susceptible F11 and one isolate each of susceptible, MDR and XDR F15/LAM4/KZN were cultured in Middlebrook 7H9 media. Human osteoblasts (SaOS-2) and human alveolar epithelial cells (A549) were exposed to these different isolates of M. tuberculosis and invasion capacity and intra-cellular multiplication rates were established. Mouse macrophage (MHS) cells exposed to M. tuberculosis H37Rv served as control. The invasion capacity of F15/LAM4/KZN representatives increased with the level of resistance. The F28 MDR strain showed similar invasion capacity as the XDR F15/LAM4/KZN for pulmonary epthelial cells, whilst the fully susceptible F11 strain displayed a propensity for osteoblasts. The differences observed may in part explain why certain strains are able to cause infection at specific extra-pulmonary sites. We postulated that the development of extra-pulmonary tuberculosis depends on the ability of the microbe to pass effectively through the alveolar epithelial lining and its affinity for cells other than those in pulmonary tissue.

The bacterial and host factors associated with extrapulmonary dissemination of Mycobacterium tuberculosis

With high morbidity and mortality worldwide, tuberculosis (TB) is still an important public health threat. The majority of human TB cases are caused by Mycobacterium tuberculosis. Although pulmonary TB is the most common presentation, M. tuberculosis can disseminate into other organs and causes extrapulmonary TB (EPTB). The dissemination of bacteria from the initial site of infection to other organs can lead to fatal diseases, such as miliary and meningeal TB. Thoroughly understanding the mechanisms and pathways of dissemination would develop therapies to prevent the lethal prognosis of EPTB (miliary and meningeal TB) and vaccines to promote the development of adaptive immunity. This review focuses on risk factors of EPTB, bacterial and host genes involved in EPTB, and potential mechanisms of M. tuberculosis extrapulmonary dissemination.

Dipterinyl calcium pentahydrate inhibits intracellular mycobacterial growth in human monocytes via the C-C chemokine MIP-1β and nitric oxide

Tuberculosis remains one of the top three leading causes of morbidity and mortality worldwide, complicated by the emergence of drug-resistant Mycobacterium tuberculosis strains and high rates of HIV coinfection. It is important to develop new antimycobacterial drugs and immunomodulatory therapeutics and compounds that enhance antituberculous immunity. Dipterinyl calcium pentahydrate (DCP), a calcium-complexed pterin compound, has previously been shown to inhibit human breast cancer cells and hepatitis B virus (HBV). DCP inhibitory effects were attributed to induction of apoptosis and/or increased production of interleukin 12 (IL-12) and granulocyte-macrophage colony-stimulating factor (GM-CSF). In this study, we tested the ability of DCP to mediate inhibition of intracellular mycobacteria within human monocytes. DCP treatment of infected monocytes resulted in a significant reduction in viability of intracellular but not extracellular Mycobacterium bovis BCG. The antimicrobial activity of DCP was comparable to that of pyrazinamide (PZA), one of the first-line antituberculosis drugs currently used. DCP potentiated monocyte antimycobacterial activity by induction of the cysteine-cysteine (C-C) chemokine macrophage inflammatory protein 1β (MIP-1β) and inducible nitric oxide synthase 2. Addition of human anti-MIP-1β neutralizing antibody or a specific inhibitor of the l-arginase-nitric oxide pathway (N(G)-monomethyl l-arginine [l-NMMA] monoacetate) reversed the inhibitory effects of DCP on intracellular mycobacterial growth. These findings indicate that DCP induced mycobacterial killing via MIP-1β- and nitric oxide-dependent effects. Hence, DCP acts as an immunoregulatory compound enhancing the antimycobacterial activity of human monocytes.

Levels of soluble VCAM-1, soluble ICAM-1, and soluble E-selectin in patients with tuberculous pleuritis

Tuberculosis is characterized by the presence of activated mononuclear cells both in the peripheral circulation and in pleural fluid. Expression and up-regulation of adhesion molecules is the basis of cell-cell adhesion in granuloma formation and in leukocyte migration to the inflammatory site. Soluble isoforms of adhesion molecules have been described, and their expression at high levels indicated an activated state. The purpose of this study was to evaluate levels of soluble adhesion molecules in serum and pleural fluid from patients with tuberculous pleural effusions, compared with non-tuberculous pleural effusions. We analysed levels of soluble vascular cell adhesion molecule-1 (s.VCAM-1), soluble intercellular adhesion molecule-1 (s.ICAM-1), and soluble E-selectin (sE-selectin) in serum and pleural fluid from patients with tuberculous pleuritis, by sandwich ELISA. Serum levels of s.ICAM-1 and s.VCAM-1 in patients with tuberculosis were higher than those in healthy controls (p < 0.001). Levels of sE-selectin levels were in the normal range compared with control groups. In pleural fluid, levels of s.VCAM-1 and s.ICAM-1 were increased in pleural effusions. Patients with tuberculous pleural effusion exhibited high levels of s.ICAM-1 compared with patients with neoplastic pleural involvement. Up-regulation of s.VCAM-1 and s.ICAM-1 in serum, along with increased levels of sE-selectin in pleural effusions from tuberculous patients, may result in transmigration of activated inflammatory cells inducing pleural damage, which may contribute to the pathological processes involved.

Characteristics of suppressor macrophages induced by mycobacterial and protozoal infections in relation to alternatively activated M2 macrophages

In the advanced stages of mycobacterial infections, host immune systems tend to change from a Th1-type to Th2-type immune response, resulting in the abrogation of Th1 cell- and macrophage-mediated antimicrobial host protective immunity. Notably, this type of immune conversion is occasionally associated with the generation of certain types of suppressor macrophage populations. During the course of Mycobacterium tuberculosis (MTB) and Mycobacterium avium-intracellulare complex (MAC) infections, the generation of macrophages which possess strong suppressor activity against host T- and B-cell functions is frequently encountered. This paper describes the immunological properties of M1- and M2-type macrophages generated in tumor-bearing animals and those generated in hosts with certain microbial infections. In addition, this paper highlights the immunological and molecular biological characteristics of suppressor macrophages generated in hosts with mycobacterial infections, especially MAC infection.

Pharmacotherapy for multidrug resistant tuberculosis

The current global concern in the treatment of tuberculosis (TB) is the emergence of resistance to the two most potent drugs namely, isoniazid and rifampicin. Emergence of multidrug resistance tuberculosis (MDR-TB) is now a health problem faced by most of the developing countries as well as developed countries across the globe. MDR-TB is a man-made disease that is caused by improper treatment, inadequate drug supplies, and poor patient supervision. HIV infection and AIDS have been implicated as important cause for this. The review of a published literature suggests that the most powerful predictor of treatment of MDR-TB is a history of treatment of TB. Although the treatment is efficacious, there are also a number of adverse effects caused by drugs used in the treatment of MDR-TB.

Mycobacteria and biological response modifiers: two sides of the relationship

With increasing use of biological response modifiers (BRMs) for various systemic inflammatory diseases there is a need to be vigilant about complications with the use of these therapies. It is important to have appropriate screening for the infections in patients requiring BRMs. However, many studies have reported benefits of certain BRMs in the treatment of infections such as tuberculosis as adjuncts. Continued research and technical advances in immunogenetics helps understand complex mechanisms in the usage of the BRMs. This article summarizes the different aspects of the relationship between mycobacterial infections and the use of various BRMs for inflammatory conditions.

Assessment of serum IL-1, IL-2 and IFN-γ levels in untreated pulmonary tuberculosis patients: role in pathogenesis

BACKGROUND AND AIMS

Tuberculosis (Tb) infection is controlled by cell-mediated immunity through mediation of IL-1, IL-2 and IFN-γ. In this study IL-1, IL-2 and IFN-γ were determined in serum samples of untreated pulmonary Tb and control group including apparently healthy individuals or contacts and normal healthy blood donors with an objective of understanding defect(s), if any, in synthesis of any of these cytokines that may lead to a diseased state of Tb.

METHODS

IL-1, IL-2 and IFN-γ were measured in serum samples of untreated Tb patients (n=33), contacts (n=19) and healthy individuals (n=20) by commercially available monoclonal antibody-based ELISA.

RESULTS

Statistically significant differences in IL-1 and IFN-γ concentrations between groups of pulmonary Tb and controls were observed, whereas no significant difference in IL-2 was seen.

CONCLUSIONS

In the present study, increased levels of cytokines in patients with pulmonary Tb are indicative of Th1 response. An increased level of cytokine (IFN-γ) in patients with untreated pulmonary Tb appears to be functionally defective.

Adjunctive therapy with interferon-gamma for the treatment of pulmonary tuberculosis: a systematic review

OBJECTIVE

To evaluate the efficacy and safety of adjunctive therapy using interferon-gamma (IFN-γ; an immunomodulator) for the treatment of pulmonary tuberculosis (TB).

METHODS

We conducted a systematic review of controlled clinical trials that compared anti-TB drugs in combination with IFN-γ with the same anti-TB drugs alone for the treatment of pulmonary TB.

RESULTS

Nine trials were identified, with IFN-γ being aerosolized or administered subcutaneously in one trial, aerosolized only in five trials, and administered intramuscularly in three trials. The methodology quality of all trials was rated 'C'. Meta-analysis of the trials with aerosolized IFN-γ showed statistical benefits on sputum negative conversion and chest radiograph: the pooled relative risk (RR) for conversion was 1.97 (95% confidence interval (CI) 1.20-3.24, p=0.008) after 1 month of treatment, 1.74 (95% CI 1.30-2.34, p=0.0002) after 2 months of treatment, 1.53 (95% CI 1.16-2.01, p=0.003) after 3 months of treatment, 1.57 (95% CI 1.20-2.06, p=0.001) after 6 months of treatment, and 1.55 (95% CI 1.17-2.05, p=0.002) at the end of treatment; the pooled RR for the chest radiograph was 1.38 (95% CI 1.10-1.17, p=0.006) at the end of treatment. For intramuscularly administered IFN-γ, meta-analysis of three trials showed its significant improvement on sputum negative conversion after 2 months of treatment. A randomized controlled trial with aerosolized and subcutaneously administered IFN-γ reported significant reductions in the symptoms of fever, wheeze, and night sweats in the IFN-γ-treated groups compared with the control group after 1 month of treatment. No patients discontinued treatment because of adverse effects caused by IFN-γ.

CONCLUSION

Adjuvant therapy using IFN-γ, especially by aerosol, might be beneficial to TB patients, but large randomized controlled trials are needed for further evaluation of its efficacy and safety considering the quality of the trials analyzed.

Male-female differences in the risk of tuberculosis in dialysis patients

AIM

To define any gender-related differences in the prevalence and risk for tuberculosis (TB) in hemodialysis (HD) patients.

METHODS

All active TB cases were recorded during a 36-month follow-up of 272 (193 male and 79 female) HD patients. Entering the study, HD patients were tested with tuberculin and 2,4-dinitrochlorobenzene, and a cell-mediated immunity (CMI) index was estimated. Relative risks (RR) for TB were calculated considering subjects from the background general population as a reference group. The independent effect of age, BMI and tuberculin sensitivity was determined using Cox's proportional hazard model.

RESULTS

Female HD patients presented significantly lower CMI indices and rates of positive Mantoux tests, but higher rates of DM, as compared to males. The male:female ratio in TB for the general and HD patients population was 1.8 and 0.6, respectively. There was a significantly lower TB prevalence in male as compared to female HD patients (7.7% vs. 11.3%), and a subsequent female predominance in risk for TB in those HD patients aged <49 and 50-69 years (M:F adjusted relative risk 0.67 and 0.53) was recorded.

CONCLUSIONS

In contrast to the general population, there is a female predominance among dialysis TB patients younger than 70 years associated with the coexistence of DM. Female gender should always be considered as a risk factor when evaluating diabetic HD patients for active TB.

Circulating adhesion molecules in tuberculosis

Leucocyte-endothelial adhesion molecules have been implicated in the pathogenesis of inflammatory diseases. To evaluate their role as markers of disease activity in tuberculosis, we have used an antigen capture ELISA to measure the serum concentrations of circulating intercellular adhesion molecule-1 (cICAM-1), E-selectin (cE-selectin) and vascular cell adhesion molecule-1 (cVCAM-1) in 34 patients with active tuberculosis (27 with pulmonary disease and seven with lymph node disease) before the commencement of standard chemotherapy, 15 subjects who had previously completed treatment for pulmonary tuberculosis, and 27 healthy volunteers. Circulating ICAM-1 and E-selectin levels were significantly elevated in patients with active tuberculosis when compared to those with treated disease (P⩽0.01), and healthy controls (P&lt; 0.02). Circulating VCAM-1 was raised in patients with active or old pulmonary tuberculosis (P&lt;0.02 versus healthy controls) but not in those with tuberculous lymphadenitis. Significant correlations were observed between the levels of cICAM-1 and cE-selectin (ρ= 0-63, P=0 0001), and between cICAM-1 and cVCAM-1 (ρ = 0.28, P=0.016). Taking the mean +2 s.d. of the serum level in healthy controls as the upper limit of normal range, circulating ICAM-1 had the best discriminative power in identifying active tuberculosis, being elevated in about 80% of patients but was raised in only 6.7% of subjects with treated disease and in 3.7% of normal subjects. Our data support the possibility that three adhesion molecules may be involved in the pathogenesis of tuberculosis and cICAM-1 may be a useful marker of disease activity.

Co-existence of Mycobacterium tuberculosis and Mycobacterium intracellulare in one sputum sample

An 81-year-old man was admitted to the hospital with a severe sore throat and a low grade fever. A chest radiograph showed bilateral diffuse reticulonodular shadows. By fluorescent stain for mycobacteria, his sputum smear showed acid-fast bacteria. The initial polymerase chain reaction (PCR) of his sputum revealed Mycobacterium intracellulare (M. intracellulare), but not Mycobacterium tuberculosis (M. tuberculosis). However, a repeat PCR was performed because M. tuberculosis could not be ruled out due to his clinical symptoms and chest imaging. The second PCR detected both M. intracellulare and M. tuberculosis. From the standpoint of infection control, this case illustrates the possibility that M. tuberculosis could be a threat if a second PCR is not done. While PCR is a useful exam for diagnosing M. tuberculosis, it can produce false negative results. Therefore, for diagnosing tuberculosis, particularly in a case such as the present case, a second PCR, which is not normally necessary, should be done.

Comparative studies on the roles of mediator molecules in expression of the suppressor activity of Mycobacterium avium complex-induced immunosuppressive macrophages against T cell and B cell mitogenic responses

Mycobacterium avium complex-induced immunosuppressive macrophages (MAC-MPhis) exhibit suppressor activity against concanavalin A-induced T cell mitogenesis (T cell Con A mitogenesis). We examined the profiles of the MAC-MPhi-mediated suppression of lipopolysaccharide-induced B cell mitogenesis (B cell LPS mitogenesis) and found the following. First, although N(G)-monomethyl-L-arginine and carboxy-PTIO effectively blocked the MAC-MPhi's suppressor activity against T cell Con A mitogenesis, MAC-MPhi's action against B cell LPS mitogenesis was only weakly affected by these NO-reducing agents. Second, B cell LPS mitogenesis was remarkably more susceptible to MAC-MPhi-derived reactive oxygen intermediates than T cell Con A mitogenesis. Third, B cell LPS mitogenesis was less susceptible to the inhibitory effects of the other MAC-MPhi-derived suppressor mediators, including free fatty acids, TGF-beta and prostaglandin E(2), than T cell Con A mitogenesis. Fourth, MAC-MPhi's suppressor activity was strongly dependent on B7-1 like molecule-mediated cell contact with target cells only in the case of T cell Con A mitogenesis. Therefore, there are significant differences in the modes of suppressor action of MAC-MPhis against T cell and B cell mitogenesis.

Role of Soluble Interleukin-2 Receptor Levels in Patients with Latent Tuberculosis

Serum soluble interleukin-2 receptor (sIL-2R) serves as a marker of disease activity in patients with tuberculosis (TB). However, little is known about its role in latent TB. The aim of this study was to assess the levels of sIL-2R in patients with latent TB and correlate them with the purified protein derivate (PPD) test results. Patients with a diagnosis of latent TB were divided into three subgroups by induration size: <10 mm, 10-20 mm, >20 mm. Blood was collected for sIL-2R assay. Findings were compared to a healthy control group. The study group consisted of 44 patients (68% male) of mean ( +/- SD) age 20 +/- 10 years, and the control group consisted of 41 subjects (42% male) aged 31 +/- 11 years. Comparison of the two groups yielded a significantly higher serum sIL-2R level in the patients (450 +/- 224 U/ml vs. 374 +/- 30 U/ml, p = 0.03). Mean sIL-2R levels were significantly correlated with the presence of latent TB (p = 0.03), and with purified protein derivative (PPD) subgroups: 387 +/- 177 U/ml for induration size <10 mm, NS; 450 +/- 238 U/ml for 10-20 mm, p = 0.04, and 605 +/- 235 U/ml for >20 mm, p < 0.0001. sIL-2R assay may serve as an additional tool to estimate the extent of the immune response in patients with latent TB.

Genetic Influence of PTPN22 R620W Polymorphism in Tuberculosis

The PTPN22 gene codes for an intracellular lymphoid-specific phosphatase (Lyp) that has a negative regulatory effect on T-cell activation. Because Lyp is an important molecule involved in the inflammatory response, and its levels are increased in cells that participate in the immune response against Mycobacterium tuberculosis, we hypothesized that the functional PTPN22 C1858T polymorphism could be a genetic factor predisposing to the development of tuberculosis (TB). Accordingly, we undertook an association study in which 113 patients with pulmonary TB and 161 matched healthy controls stratified by the tuberculin skin test (TST) were examined. Significant skewing was observed when T allele frequencies of patients with TB and all controls were compared (P=0.04, odds ratio=0.3; 95% confidence interval=0.08-1.04) and frequencies of patients with TB and TST+ healthy controls were compared (P=0.01, odds ratio=0.2; 95% confidence interval=0.05-0.79). No stratification was detected between patients and control samples. These results suggest that the T allele may be a factor protecting against development of TB once the immune system recognizes M. tuberculosis (i.e., TST+ individuals), whereas the C allele may be a risk factor for development of overt TB. The results also indicate that an association opposite that between the PTPN22 polymorphism and TB exists between TB and autoimmunity.

The role of B7 molecules in the cell contact-mediated suppression of T cell mitogenesis by immunosuppressive macrophages induced with mycobacterial infection

We found previously that immunosuppressive macrophages (Mphis) induced by Mycobacterium intracellulare infection (MI-Mphis) transmitted their suppressor signals to target T cells through cell contact with target T cells. In this study, we examined what kinds of Mphi surface molecules are required for such cell-to-cell interaction. First, it was found that a B7-1-like molecule (B7-1LM) recognizable with one of three test clones of anti-B7-1 monoclonal antibodies (mAbs) was required for expression of the Mphi suppressor activity. Neither anti-B7-2, anti-ICAM-1, nor anti-VCAM-1 mAb blocked the Mphi suppressor activity. Second, MI-Mphis increased the expression of B7-1LM in parallel with the acquisition of the suppressor activity. Moreover, MI-Mphis bound with target T cells in a B7-1LM-dependent fashion. Third, mAb blocking of CTLA-4 on target T cells did not reduce the suppressor activity of MI-Mphis, suggesting the role of a putative molecule on target T cells other than CTLA-4 as the receptor for B7-1LM of MI-Mphis. Fourth, concanavalin A (Con A) stimulation of MI-Mphis was needed for effective cell contact with target T cells and subsequent expression of the suppressor activity of MI-Mphis. Fifth, the Con A-induced increase in the suppressor activity of MI-Mphis was inhibited by KN-62 but not by herbimycin A, H-7, nor H-88, indicating that Con A-induced up-regulation of MI-Mphi function is mediated by calmodulin-dependent protein kinase II or ATP/P2Z receptors, but independent of protein tyrosine kinase, protein kinase C, and protein kinase A. These findings indicate that a B7/CTLA-4-independent mechanism is needed for the transmission of the suppressor signals from MI-Mphis to target T cells.

Atypical cutaneous findings in a patient with systemic lupus erythematosus

A previously diagnosed systemic lupus erythematosus patient presented with arthralgia, skin rash and muscular weakness. When treated with high-dose corticosteroids and methotrexate she improved, except for a persistent lesion in the hand which evolved into a profound ulcer, along with tender subcutaneous nodules in the calf. A skin biopsy disclosed necrotizing vasculitis with giant cell granuloma revealing acid fast positive bacteria on ziels nilsen staining. A chest X-ray disclosed miliary tuberculosis (TB). The patient was diagnosed as miliary TB with prominent cutaneous involvement and treated with four anti-tuberculous drugs with slow resolution of her systemic, pulmonary and skin signs.

Shifts of T4/T8 T lymphocytes from BAL fluid and peripheral blood by clinical grade in patients with pulmonary tuberculosis

OBJECTIVES

We investigated the shifts of T4/T8 lymphocytes from BAL fluid (BALF) and peripheral blood by the clinical grade of pulmonary tuberculosis (TB), which is determined by factors such as extent of pulmonary involvement, fever, and loss of body weight.

MATERIALS AND METHODS

In order to explore these questions, BALF was collected from 45 patients presenting with active pulmonary TB and 14 healthy control subjects. The percentages for T-lymphocyte subpopulations, including CD4(+), CD8(+), and CD3(+) T cells, were measured using two-color flow cytometry.

RESULTS

A higher percentage of CD3(+)CD4(+) T lymphocytes, with a relatively lower percentage of CD3(+)CD8(+) T lymphocytes, was revealed for the patients with a higher grade of pulmonary TB, compared to patients with a lower grade of pulmonary TB, resulting in an increased BALF C4(+)/CD8(+) ratio. By contrast, a higher percentage of CD3(+)CD8(+) T lymphocytes with a relatively low percentage of CD3(+)CD4(+) T lymphocytes was demonstrated for these patients with a higher grade of pulmonary TB, resulting in a decreased peripheral blood CD4(+)/CD8(+) ratio.

CONCLUSIONS

Our findings suggest that compartmentalization of the CD4(+) T lymphocytes in the infected lungs may occur for patients with higher grades of pulmonary TB.

Identification of a chemotactic, MCP-1-like protein from Mycobacterium avium

In the immunocompetent host, Mycobacterium avium is responsible for chronic localized pulmonary disease, which is characterized by the presence of increased numbers of activated T cells and macrophages in the lungs. M. avium organisms as well as sonic extracts of M. avium were found to act as chemoattractants for THP-1 cells as well as monocytes, monocyte-derived macrophages and alveolar macrophages obtained from normal human donors in an in vitro chemotaxis assay, where a significantly higher number of cells were found in wells containing M. avium compared to control wells. Proteolytic treatment of M. avium sonicate resulted in significant loss (50%) of chemotactic activity. Monoclonal antibodies against recombinant human monocyte chemoattractant protein-1 (MCP-1) were found to cross-react with a 34-kDa protein of M. avium sonicate on Western blot and inhibit M. avium sonicate-mediated chemotaxis of THP-1 cells (47%). These data suggest the presence of an 'MCP-1 like' molecule on M. avium. Recruitment of host immune regulatory cells to the site of infection by pathogens may be involved in generating a local immune response or may be a bacterial strategy for survival within the host by recruiting the cells that they infect, i.e. macrophages.

Apoptosis modulation by mycolic acid, tuberculostearic acid and trehalose 6,6'-dimycolate

The object of our study is to demonstrate that some components of M. tuberculosis, such as cord factor or mycolic acid or whole bacteria can prolong cell survival compared to controls. The cells treated with cord factor or mycolic acid at a concentration of 5 microg/ml were 65+/-8% viable reaching 70+/-8% at a concentration of 10 microg/ml. The cells treated with heat killed mycobacteria were 70+/-8% viable; while control cells exhibited a viability 50+/-7%. Conversely, tuberculostearic acid induced early cell death. The results also demonstrated a dose-dependent effect on the viability or induction of macrophage apoptosis. We also showed that prolonged viability of the treated cells with mycolic acid or cord factor (+20+/-4% and +25+/-5%, respectively) was correlated with a significant increase in Bcl-2 expression. The treated cells with whole bacteria presented a Bcl-2 expression of 40+/-6%, while Fas expression was not changed compared to controls. This study confirm that at the site of mycobacterial infection, necrosis, apoptosis or prolonged survival of the cells depend on the quantity and quality of the molecules expressed by the mycobacteria; whether necrosis or apoptosis or prolonged survival is more or less favorable to the host likely depends on several factors regarding the inflammatory and immune response, both markedly stimulated by mycobacteria.

Downmodulation of CD18 and CD86 on macrophages and VLA-4 on lymphocytes in experimental tuberculosis

Development and evaluation of new vaccines and immunotherapy against tuberculosis demand a better understanding of the immune mechanisms in this disease. Costimulatory signals and intercellular contact seem to be pivotal in determining whether recognition of antigen by T cells leads to activation or anergy. In this paper, we show that virulent M. tuberculosis H37Rv downmodulates the ex vivo expression of CD18 and CD86 on peritoneal macrophages and VLA-4 on lymphocytes but does not disturb the in vitro production of interleukin (IL)-12 and interferon (IFN)-gamma after intraperitoneal infection. In addition, splenocytes from infected mice produce IL-10, while the expression of cell surface receptors is unchanged. The interplay among IL-12, IFN-gamma and IL-10 in vivo and the downmodulation of cell-surface receptors during the infection at the inflammatory site may contribute to the explanation of the maintenance of infection.

Enhancement of innate immunity against Mycobacterium avium infection by immunostimulatory DNA is mediated by indoleamine 2,3-dioxygenase

Bacterial DNA and its synthetic immunostimulatory oligodeoxynucleotide analogs (ISS-ODN) activate innate immunity and promote Th1 and cytotoxic T-lymphocyte immune responses. Based on these activities, we investigated whether ISS-ODN could modify the course of Mycobacterium avium infection. M. avium growth in vitro was significantly inhibited by ISS-ODN treatment of human and mouse macrophages, and M. avium growth in vivo was similarly inhibited in C57BL/6 mice treated with ISS-ODN. This protective effect of ISS-ODN was largely independent of tumor necrosis factor alpha (TNF-alpha), interleukin 12 (IL-12), nitric oxide, NADPH oxidase, alpha/beta interferon (IFN-alpha/beta), and IFN-gamma. In contrast, we found that the induction of indoleamine 2,3-dioxygenase (IDO) was required for the antimycobacterial effect of ISS-ODN. To evaluate the potential for synergism between ISS-ODN and other antimycobacterial agents, treatment with a combination of ISS-ODN and clarithromycin (CLA) was tested in vitro and in vivo. ISS-ODN significantly enhanced the therapeutic effect of CLA in both human and mouse macrophages and in C57BL/6 mice. This study newly identifies IDO as being involved in the antimicrobial activity of ISS-ODN and suggests the usefulness of ISS-ODN when used in combination with conventional chemotherapy for microbial infections.

Expression of IFN-gamma-inducible protein; monocyte chemotactic proteins 1, 3, and 4; and eotaxin in TH1- and TH2-mediated lung diseases

BACKGROUND

Chemokines are involved in the influx of leukocytes into the airways in inflammatory lung diseases. The differential cell recruitment characteristic of T(H)1 versus T(H)2 immune responses may be associated with differential chemokine expression.

OBJECTIVE

We investigated the expression of chemokines; monocyte chemotactic proteins (MCPs) 1, 3, and 4; eotaxin; and IFN-gamma-inducible protein 10 (IP-10) in both T(H)1- and T(H)2-mediated lung diseases.

METHODS

By using immunocytochemistry and in situ hybridization, we examined the protein and mRNA expression, respectively, in bronchoalveolar lavage and biopsy samples in subjects with asthma, tuberculosis, sarcoidosis, and chronic bronchitis.

RESULTS

Increased immunoreactivity and mRNA expression of IP-10 and of the MCPs was found in the bronchoalveolar lavage fluid and biopsy specimens of subjects with asthma and tuberculosis compared with that of control subjects (P <.005). IP-10, however, was particularly increased in subjects with sarcoidosis (P <.001). Eotaxin, on the other hand, was increased only in patients with asthma when compared with control subjects (P <.005).

CONCLUSION

This study demonstrates that MCP-1, MCP-3, and MCP-4 expression is not specifically associated with lung diseases characterized by a particular cytokine profile. In contrast, IP-10 is mostly expressed in T(H)1-mediated diseases, and eotaxin expression seems to be specifically associated with lung diseases of a T(H)2 cytokine profile.

Nitric oxide modulates interleukin-1beta and tumour necrosis factor-alpha synthesis, and disease regression by alveolar macrophages in pulmonary tuberculosis

Pretreatment with nitric oxide synthase (NOS) inhibitors profoundly increases mortality, bacterial burden and pathological tissue damage in mice infected with Mycobacterium tuberculosis. Nitric oxide (NO) production is enhanced in alveolar macrophages (AM) of tuberculosis (TB) patients. Interleukin (IL)-1beta and tumour necrosis factor (TNF)-alpha released from AM are involved in the immune response to mycobacterial infection. The aim of the present study was to examine whether NO is implicated in IL-1beta and TNF-alpha synthesis by AM and related to the resolution of disease activity in TB patients. Purified AM were retrieved by bronchoalveolar lavage from TB patients and normal subjects, and cultured in the presence or absence of a NO inhibitor, NG-monomethyl-L-arginine (L-NMMA). The release of IL-1beta and TNF-alpha, and their mRNA expression were determined by enzyme-linked immunosorbent assay (ELISA) and northern analysis, respectively. The level of nitrite released into the culture medium was determined. The rate of disease regression was evaluated by serial chest radiography. The release of nitrite, IL-1beta and TNF-alpha was much greater from AM of TB patients than normal subjects. NG-monomethyl-L-arginine inhibited the production of nitrite as well as IL-1beta and TNF-alpha in TB patients. The mRNA expression for IL-1beta and TNF-alpha was upregulated in TB patients and was depressed by L-NMMA. Immunocytochemistry using a monoclonal antibody against nuclear factor-kappaB (NF-kappaB) subunit p65 showed NF-kappaB was highly expressed and translocated to the nuclei of AM in TB patients, and was inhibited by L-NMMA. An inhibition of NF-kappaB by pyrrolidine dithiocarbamate attenuated IL-1beta and TNF-alpha synthesis. More generation of NO from cultured AM increased the disease regression in TB patients. We conclude that the enhanced NO generation by AM of TB patients may play an autoregulatory role in amplifying the synthesis of pro-inflammatory cytokines, probably through the activation of NF-kappaB. Nitric oxide may also play an important role in resistance to M. tuberculosis infection.

Effect of oestrogen on Mycobacterium avium complex pulmonary infection in mice

The purpose of the present study was to elucidate the role of oestrogen in the pathogenesis of Mycobacterium avium complex (MAC) pulmonary disease, which occurs most frequently in postmenopausal women. The study was carried out in a murine infectious model using ovariectomized DBA/2 female mice. Infection with MAC was established by intratracheal administration of bacilli. In some experiments, ovariectomized mice were treated with exogenous 17 beta-estradiol (E2). The number of bacilli in the lungs of infected mice which received ovariectomy was significantly larger than that in the lungs of sham-operated control mice, and treatment of ovariectomized mice with exogenous E2 restored the burden of bacilli to the same level as that in the sham-operated control mice. We next examined the effect of E2 in vitro using bone marrow-derived macrophages obtained from DBA/2 female mice. The macrophages showed bacteriostatic activity against MAC after treatment with interferon-gamma (IFN-gamma) and this activity was further enhanced by the exogenous addition of E2 to the culture medium. In parallel with these findings, E2 augmented the production of reactive nitrogen intermediates (RNI) by macrophages pretreated with IFN-gamma and stimulated with MAC, as shown by evaluating nitrite production and inducible nitric oxide synthase mRNA expression. These findings taken together suggest that absence of endogenous oestrogen appears to be responsible for the development of MAC pulmonary disease in this mouse model and that the enhancement by E2 of anti-MAC activity of murine macrophages induced through increased RNI production may play some role in resistance to MAC infection.

Roles of tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), and IL-10 in the modulation of intercellular adhesion molecule-1 (ICAM-1) expression by macrophages during mycobacterial infection

Profiles of ICAM-1 expression on cultured murine peritoneal macrophages infected with Mycobacterium avium complex (MAC) were examined, with special reference to modulating roles of TNF-alpha, TGF-beta, and IL-10. When macrophages were infected with MAC, ICAM-1 expression, measured by microscopic counting of ICAM-1+ macrophages stained with anti-ICAM-1 antibody, ELISA, and flow cytometric analysis, was rapidly increased, peaking at day 3 (early-phase up-regulation) due to endogenous TNF-alpha, and thereafter gradually declined to the normal level within 1 week or more (late-phase down-regulation). The late-phase ICAM-1 down-regulation was also seen in macrophages phagocytosing heat-killed MAC and those stimulated with lipopolysaccharide but not in macrophages phagocytosing latex beads. ICAM-1 mRNA expression was augmented markedly at day 1 after MAC infection and thereafter decreased. While TNF-alpha and IL-10 production by MAC-infected macrophages was observed during the first 3 days, TGF-beta production was initiated from day 3 and continued until day 14. Exogenously added TGF-beta strongly inhibited the early-phase increase in ICAM-1 expression by infected macrophages, and the blockade of endogenous TGF-beta with anti-TGF-beta antibody markedly inhibited late-phase ICAM-1 down-regulation. Moderate blocking effect was also observed for anti-IL-10 antibody. On the other hand, late-phase ICAM-1 down-regulation was not prevented by the addition of exogenous TNF-alpha. Therefore, TGF-beta and IL-10, especially the former, appear to play active roles in the late-phase down-regulation of ICAM-1 in MAC-infected macrophages during long-term cultivation.

Release of monocyte chemoattractant protein (MCP)-1 by a human alveolar epithelial cell line in response to mycobacterium avium

Clinical strains of Mycobacterium avium isolated from patients with acquired immunodeficiency syndrome, but not a non-clinical laboratory strain (ATCC 25291), were found to stimulate the human alveolar epithelial cell line A549, to produce monocyte chemoattractant protein (MCP)-1. A549 cells were also found to produce elevated levels of MCP-1 in response to sonicates of the clinical strains of M. avium, and surprisingly, the non-clinical strain as well. However, sonic extracts of the clinical strains were found to induce significantly higher levels of MCP-1 production compared to extracts of the non-clinical strain (P < 0.001). These data suggest the existence of strain-related differences in antigen expression by M. avium. The clinical and non-clinical strains of M. avium were found to attach and invade, but not replicate in A549 cells indicating that MCP-1 production by A549 cells does require the presence of viable, replicating organisms. Activation of alveolar epithelial cells by exposure to M. avium resulting in the production of chemokines which recruit inflammatory cells to the site of infection may be an important regulatory pathway for the activation of pulmonary host defense.

Hypodense alveolar macrophages in patients with diabetes mellitus and active pulmonary tuberculosis

SETTING

Alveolar macrophages (AM), a heterogeneous cell population, play a critical role in eliminating mycobacterial infections in collaboration with lymphocytes. Patients with diabetes mellitus (DM) show increased susceptibility to pulmonary tuberculosis (TB) infection. It is still uncertain whether there is a defect in T cell or AM activation in patients with DM against TB infection.

OBJECTIVE

To study the difference in activation status of AM and T cells between patients with TB + DM and TB alone.

METHOD

The heterogeneity of AM from 14 patients with TB + DM, 9 with TB alone, 10 normal subjects and 8 DM alone patients, was studied using Percoll density fractionation. The intracellular H2O2 production of AM before and after stimulation with phorbol myristate acetate (PMA) or F-Met-Leu-Phen (FMLP) was assayed by loading cells with 2',7'-dichlorofluorescin (DCFH) and analyzed by flow cytometry. Lymphocytes subsets (CD3, CD4, CD8) and their activation status (CD25) in bronchoalveolar lavage were also measured.

RESULTS

The proportion of the least dense AM (< 1,030 g/ml) and the magnitude of DCFH oxidation of AM was higher in TB patients than in normal subjects, regardless of DM. Patients with TB + DM had a significantly lower proportion of the least density AM fraction than TB alone patients, regardless of disease extent. Among TB patients, the proportion of the least dense AM was inversely correlated with the bacterial load on sputum and the disease extent on chest radiograph. Stimulation of AM with PMA or FMLP induced an increase in the hypodense AM subpopulations and enhanced intracellular H2O2 generation in patients with TB + DM and to a similar extent in normal subjects, but not in patients with TB alone. There was no significant difference in CD3 numbers, CD4/CD8 ratio, and CD25+ cells between patients with TB alone and TB + DM. The activation status of AM or T lymphocytes from DM alone patients was not significantly different from those from normal subjects.

CONCLUSION

Hypodense subpopulations of AM increase in active TB patients and are related to the disease severity as well as activation status of AM. AM in TB patients complicated with DM was less activated, and may be contributory to the susceptibility to mycobacterial infection.

Preferential recruitment of phagocytes into the lung of patients with advanced acquired immunodeficiency syndrome and tuberculosis

Limited data are available on the cellular and immunocytological characteristics of bronchoalveolar lavage (BAL) fluid in individuals infected with the human immunodeficiency virus (HIV) and pulmonary tuberculosis (TB). The immune host response against tuberculosis in early HIV-infection may differ from that in later stages of HIV disease, as is strongly suggested by different clinical and radiographic patterns. We studied the cellular elements in the lungs of 15 HIV-infected patients with advanced immunosuppression and pulmonary tuberculosis (TB/AIDS). The findings were compared with data from four other groups: 1) 15 HIV-seronegative patients with pulmonary TB; 2) 12 HIV-seropositive TB patients without previous AIDS-defining illnesses and with CD4+ >200 cells mm(-3); 3) five AIDS patients without pulmonary lesions; and 4) five healthy controls. BAL fluid and differential cell counts, as well as lymphocyte subsets, were determined. Despite a low CD4/CD8 ratio, the TB/AIDS group had a higher absolute number of CD8+ lymphocytes in the BAL fluid than the other groups. Alveolar macrophages and neutrophils were significantly increased in TB/AIDS patients compared to control groups. The number of eosinophils was increased in TB/HIV--patients but not in TB/AIDS patients. We conclude that tuberculosis in late stage HIV-infected patients has a distinct inflammatory cell profile, suggesting an enhanced compensatory mechanism that amplifies the unspecific inflammatory reaction.

Lymphocyte populations in tuberculous pleural effusions

Different systemic and local responses to mycobacterial antigens suggest an active compartmentalization of responsive lymphocytes to tubercular antigens. This fact, observed in pleuritic processes, raises doubts about the accuracy of information obtained in the study of cells taken solely from peripheral blood. For this reason we decided to study the concept of compartmentalization in 140 patients suffering from pleural effusions. Patients were classified into six groups according to the aetiology of the effusion: group I, tuberculous, n = 23; group II, paraneoplastic, n = 41; group III, metapneumonic empyematous, n = 5; group IV, transudate, n = 38; group V, miscellaneous exudate, n = 19; group VI, unknown aetiology, n = 14. In each group we studied the lymphocyte population by using flow cytometry with doubly fluorescent monoclonal antibodies: B [expressing human lymphocyte antigen (HLA)-DR on the surface], T (CD3+), CD4+ and CD8+, and the subpopulation of activated T lymphocytes (together expressing CD3 and HLA-DR on the surface) (CD3+DR+). The study of these subpopulations in peripheral blood did not yield valuable results, but the CD3+DR+ population in pleural fluid demonstrated a diagnostic efficiency of 84% [positive predictive value (PPV) 51%, negative predictive value (NPV) 96%] at a cut-off value of 80.4 cells/mm3. The CD3+DR+ pleural fluid/peripheral blood ratio demonstrated an efficiency of 83% (PPV 50%, NPV 96%), and showed a statistically significant difference (P < 0.02) with regard to all the diagnostic groups, with the exception of the paraneoplastic effusions. The lymphocytic subpopulations study confirms the concept of compartmentalization in tuberculous pleuritis, as shown by the greater number of activated T lymphocytes present in pleural fluid in comparison with peripheral blood in tuberculous pleuritis, a 98% efficiency of adenosine deaminase (ADA) determination in pleural fluid versus a 50% value in peripheral blood, predominance of helper cells (CD4+) in pleural fluid and suppressor cells (CD8+) in peripheral blood, a greater CD4+/CD8+ ratio in pleural fluid than in peripheral blood, and a significant correlation of ADA-CD3+DR+ in pleural fluid, which does not occur in peripheral blood.

Role of CD40 ligand in Mycobacterium avium infection

Mycobacterium avium is a common opportunistic pathogen in immunocompromised patients such as those infected with human immunodeficiency virus. Although M. avium is an intracellular organism replicating predominantly in macrophages, disseminated M. avium infection is seen in AIDS patients with CD4(+) cell counts of <50 cells/microliters, suggesting a possible involvement of a T cell-macrophage interaction for the elimination of M. avium. To determine whether CD40-CD40 ligand (CD40L) interactions play a role in M. avium infection, we studied the ability of CD40L to restrict M. avium replication in human monocyte-derived macrophages (MDM) in vitro. MDM were infected with M. avium and cocultured with CD40L-transfected 293 cells for 7 days. Intracellular growth of M. avium in these MDM was assessed by colony counting. CD40L-expressing cells inhibited growth of M. avium in MDM by 86.5% +/- 4.2% compared to MDM cultured with control cells. These findings were verified by assays using purified, soluble recombinant human CD40L (CD40LT). CD40LT (5 micrograms/ml) inhibited intracellular growth of M. avium by 76.9% +/- 18.0% compared to cells treated with medium alone. Inhibition by CD40LT was reduced by monoclonal antibodies (MAbs) against CD40 and CD40L. The inhibitory effect of CD40LT was not accompanied by enhancement of interleukin-12 (IL-12) production by M. avium-infected MDM, while CD40L-expressing cells stimulated IL-12 production by these cells. Treatment of M. avium-infected mice with MAb against murine CD40L resulted in recovery of larger numbers of organisms (0.8 to 1.0 log) from the spleens, livers, and lungs of these animals compared to infected mice which received normal immunoglobulin G. These results indicate that CD40-CD40L signaling may be an important step in host immune response against M. avium infection.

The T Cell-Specific CXC Chemokines IP-10, Mig, and I-TAC Are Expressed by Activated Human Bronchial Epithelial Cells

Recruitment of activated T cells to mucosal surfaces, such as the airway epithelium, is important in host defense and for the development of inflammatory diseases at these sites. We therefore asked whether the CXC chemokines IFN-induced protein of 10 kDa (IP-10), monokine induced by IFN-γ (Mig), and IFN-inducible T-cell α-chemoattractant (I-TAC), which specifically chemoattract activated T cells by signaling through the chemokine receptor CXCR3, were inducible in respiratory epithelial cells. The effects of proinflammatory cytokines, including IFN-γ (Th1-type cytokine), Th2-type cytokines (IL-4, IL-10, and IL-13), and dexamethasone were studied in normal human bronchial epithelial cells (NHBEC) and in two human respiratory epithelial cell lines, A549 and BEAS-2B. We found that IFN-γ, but not TNF-α or IL-1β, strongly induced IP-10, Mig, and I-TAC mRNA accumulation mainly in NHBEC and that TNF-α and IL-1β synergized with IFN-γ induction in all three cell types. High levels of IP-10 protein (&gt;800 ng/ml) were detected in supernatants of IFN-γ/TNF-α-stimulated NHBEC. Neither dexamethasone nor Th2 cytokines modulated IP-10, Mig, or I-TAC expression. Since IFN-γ is up-regulated in tuberculosis (TB), using in situ hybridization we studied the expression of IP-10 in the airways of TB patients and found that IP-10 mRNA was expressed in the bronchial epithelium. In addition, IP-10-positive cells obtained by bronchoalveolar lavage were significantly increased in TB patients compared with normal controls. These results show that activated bronchial epithelium is an important source of IP-10, Mig, and I-TAC, which may, in pulmonary diseases such as TB (in which IFN-γ is highly expressed) play an important role in the recruitment of activated T cells.

Lack of T-lymphocytosis and poor interferon gamma production in BAL fluid from HIV-negative immunocompetent patients with pulmonary non-tuberculous mycobacteriosis

Very little is known about the pathogenesis of pulmonary non-tuberculous mycobacteriosis in immunocompetent individuals. Local inflammatory response was assessed by examining bronchoalveolar lavage fluid from 13 HIV-negative patients (12 F) without known cell-mediated immunosuppression, aged 48-72 y (median age 60 y), with non-tuberculous lung mycobacteriosis. Macrophages, lymphocytes, polymorphonuclear neutrophils and eosinophils in bronchoalveolar lavage fluid were analysed morphologically, and the subsets of T-lymphocytes (CD3+, CD4+, CD8+), HLA-DR+, B-lymphocytes (CD19+) and CD16+/CD56+ cells (natural killer, NK cells) were analysed by flow cytometry. Interleukin-1 beta (IL-1beta), IL-2, IL-4, IL-6, IL-8, IL-10 and interferon-gamma (IFN-gamma) levels were assessed by ELISA. The total number of cells/ml was significantly higher in BAL fluid from the patients (median value=880 x 10(3)/ml) compared to six healthy controls (200 x 10(3)/ml). The polymorphonuclear neutrophil population was significantly increased in the patients both proportionally and in the count/ml. The proportion of macrophages was significantly reduced in the patients but not the count/ml. The count of lymphocytes/ml was significantly higher in the patients but the proportion of lymphocytes was unchanged. No significant difference was seen in the relative proportion of NK cells, B- or T-lymphocytes and HLA-DR+ compared to the healthy controls. The IL-1beta and IL-8 levels were significantly increased in the patients. No differences were seen between the patients and controls in the leukocyte or lymphocyte subsets in peripheral blood. The local inflammatory response in BAL fluid from the studied patients was characterized by granulocytosis, and increase in the IL-1beta and IL-8 levels. There was no specific T-cell response.