T4 lymphopenia in human tuberculosis

Insights in tuberculosis immunology: Role of NKT and T regulatory cells

Background

Tuberculosis (TB) control is challenging due to poor drug compliance and emerging resistance. The need of the hour is to determine the prediction of disease cure and relapse. Patients' immune response is crucial to the disease outcome. This study was designed to study the immune profile of TB patients during treatment and cure.

Methods

The cross-sectional study included newly diagnosed pulmonary TB patients and healthy controls. Levels of serum cytokines/chemokines (Th1/Th2/Th17) were measured by BD cytometric bead array. The cell surface markers assessed in the study were CD3, CD4, CD8, CD16, CD56, and BD human regulatory T cell cocktail (CD4/CD25/CD127).

Results

Data analysis observed statistically significant differences in CD3dim/CD56 + natural killer T (NKT) among TB patients with significantly low levels in healthy controls and after treatment completion (P < 0.0001). The analysis also revealed a high percentage of CD3dim/CD56 + NKT in fast responders. The percentage of T regulatory was found to be high in patients when compared with healthy controls; the values were statistically significant (0.0002). Interleukin-6 was significantly associated with the disease (P < 0.0485).

Discussion

A comprehensive understanding of role of CD3dim/CD56+ NKT in antimycobacterial immunity may enable new possibilities for NK cell-based prophylactic and/or therapeutic strategies against TB.

CD3, CD4, CD8, CD19 and CD16/CD56 positive cells in tuberculosis infection and disease: Peculiar features in children

Pathogenesis of mycobacterial infection has been extensively studied determining the fundamental role of host immunocompetence in disease progression. Cellular adaptive immunity, in particular CD4+ cells, has shown to be crucial in the host defence. A role of cytotoxic lymphocytes and humoral immunity has also been established. However, few studies have been performed in low endemic countries on immunological correlates of tuberculosis in paediatric patients. The present study aims to fill this gap analysing the distribution and the absolute values of the main lymphocyte subpopulations (CD3+, CD4+, CD8+, CD19+ and CD16+/CD56+) in the different stages of tubercular infection in human immunodeficiency virus–negative children living in low tubercular endemic countries. Results obtained in children with latent tuberculosis, active tuberculosis and healthy controls were compared. Moreover, quantitative analysis of interferon-γ levels of mitogen-induced response was carried out within the different study groups. The aim of this analysis was to enforce the comprehension of immune modifications subsequent to Mycobacterium tuberculosis infection. The major finding of our study was CD3+ and CD4+ absolute and percentage depletion in children with active tuberculosis versus healthy controls. Moreover, severe forms of active tuberculosis showed a marked reduction in the CD4+ percentage in the context of a systemic impairment which affects globally the absolute count of all peripheral lymphocyte subsets tested. A relative increase of natural killer cells was proved in infected patients, whereas no differences in B cells among the study groups were detected. Mitogen-induced interferon-γ levels were significantly higher in children with latent tuberculosis when compared to active tuberculosis and healthy controls, demonstrating effective immune activation in those patients able to control the infection.

Natural killer cell activation distinguishes Mycobacterium tuberculosis-mediated immune reconstitution syndrome from chronic HIV and HIV/MTB coinfection

BACKGROUND

With increased access to antiretroviral treatment (ART), immune reconstitution inflammatory syndrome (IRIS) in Mycobacterium tuberculosis (MTB)-infected populations remains a clinical challenge. We studied a cross-sectional cohort of HIV-infected subjects in Johannesburg (South Africa) to help define the immune correlates that best distinguish IRIS from ongoing MTB cases.

METHODS

We studied HIV+ subjects developing MTB-related unmasking tuberculosis-related immune reconstitution inflammatory syndrome (uTB-IRIS) after ART initiation; control groups were subjects with HIV and HIV/tuberculosis-coinfected subjects with comparable ART treatment. Testing was conducted with whole blood-based 4-color flow cytometry and plasma-based Luminex cytokine assessment.

RESULTS

Natural killer cell activation, C-reactive protein, and interleukin 8 serum concentration were significantly higher in uTB-IRIS subjects compared with both control groups. In addition, all MTB-coinfected subjects, independent of clinical presentation, had higher neutrophils and T-cell activation, together with lower lymphocytes, CD4⁺ T-cell, and myeloid dendritic cell counts. Using conditional inference tree analysis, we show that elevated natural killer cell activation in combination with lymphocyte count characterizes the immunological profile of uTB-IRIS.

CONCLUSION

Our results support a role for innate immune effectors in the immunopathogenesis of unmasking MTB-related IRIS and identify new immune parameters defining this pathology.

Clonal expansion of CD8+ effector T cells in childhood tuberculosis

The role of CD8(+) T cells in human tuberculosis (TB) remains elusive. We analyzed the T cell repertoire and phenotype in 1) children with active TB (< or =4 years), 2) healthy latently Mycobacterium tuberculosis-infected children, and 3) noninfected age-matched (tuberculin skin test-negative) controls. Ex vivo phenotyping of T cell subpopulations by flow cytometry revealed a significant increase in the proportion of CD8(+)CD45RO(-)CD62L(-)CD28(-)CD27(-) effector T cells (T(EF)) in the peripheral blood of children with active TB (22.1 vs 9.5% in latently M. tuberculosis-infected children, vs 8.5% in tuberculin skin test-negative controls). Analyses of TCR variable beta-chains revealed markedly skewed repertoires in CD8(+) T(EF) and effector memory T cells. Expansions were restricted to single TCR variable beta-chains in individual donors indicating clonal growth. CDR3 spectratyping and DNA sequencing verified clonal expansion as the cause for CD8(+) effector T cell enrichment in individual TB patients. The most prominent enrichment of highly similar T(EF) clones (>70% of CD8(+) T(EF)) was found in two children with active severe TB. Therefore, clonal expansion of CD8(+) T(EF) occurs in childhood TB with potential impact on course and severity of disease.

Lymphocyte subpopulations in pulmonary tuberculosis patients

Protection against Mycobacterium tuberculosis is based on cell-mediated immunity, most importantly involving CD4⁺ and CD8⁺ T-cell subsets. The aim of this study was to evaluate CD4⁺ and CD8⁺ T-cell profiles and CD19⁺ and CD3⁻CD(16+56)⁺ populations in patients with pulmonary tuberculosis. CD4⁺ and CD8⁺ T cells, B-lymphocytes, and natural killer (NK) cells were evaluated in 75 active (APTB) and 25 inactive (IPTB) pulmonary tuberculosis cases and 20 healthy subjects (HCs). The results were compared at different stages of antituberculosis treatment in the APTB patients and also according to X-ray findings in the newly diagnosed APTB patients. The percentages of CD4⁺ T cells were significantly lower (P < .01) and those of CD3⁻CD(16 + 56)⁺ cells were significantly higher (P < .01) in APTB patients than in HCs. CD8⁺ T cells were significantly decreased (P < .05), and CD3⁻CD(16+56)⁺ cells were significantly increased (P < .01), in IPTB patients compared to HCs. The percentages of CD4⁺, CD8⁺, CD3⁻CD19⁺, and CD3⁻CD(16+56)⁺ cells showed no differences at different times of the antituberculosis regimen, and different stages of newly diagnosed APTB patients. APTB patients have a reduced percentage of circulating CD4⁺ T cells and an increased percentage of NK cells compared with healthy individuals. These cells could play important roles in the immune response to M tuberculosis infection.

Changes in leucocyte and lymphocyte subsets during tuberculosis treatment; prominence of CD3dimCD56+ natural killer T cells in fast treatment responders

The immune responses against pulmonary tuberculosis are still poorly defined. This study describes changes in leucocyte and lymphocyte subsets during treatment to find reliable immunological markers for the disease and treatment response. Flow cytometric peripheral blood immune phenotyping, routine haematology and sputum microbiology were performed on 21 HIV-negative adult tuberculosis (TB) patients with positive sputum cultures during therapy in comparison with 14 healthy purified protein derivative (PPD)-positive volunteers. Patients at diagnosis showed high absolute neutrophil and monocyte counts which fell during treatment but low lymphocyte subset counts which increased [except natural killer (NK) and NK T cells]. High counts of a population of CD3(dim)/CD56+ NK T cells at diagnosis correlated significantly with negative sputum culture after 8 weeks of treatment. A multivariate classification technique showed improved correlation when NK cells were taken into account. In conclusion, peripheral blood white cell counts change significantly during treatment and counts at diagnosis, especially CD3(dim)/CD56+ NK T cells, hold promise in predictive models of TB treatment response.

The use of immunomodulators as an adjunct to antituberculous chemotherapy in non-responsive patients with osteo-articular tuberculosis

We studied 51 patients with osteo-articular tuberculosis who were divided into two groups. Group I comprised 31 newly-diagnosed patients who were given first-line antituberculous treatment consisting of isoniazid, rifampicin, ethambutol and pyrazinamide. Group II (non-responders) consisted of 20 patients with a history of clinical non-responsiveness to supervised uninterrupted antituberculous treatment for a minimum of three months or a recurrence of a previous lesion which on clinical observation had healed. No patient in either group was HIV-positive. Group II were treated with an immunomodulation regime of intradermal BCG, oral levamisole and intramuscular diphtheria and tetanus vaccines as an adjunct for eight weeks in addition to antituberculous treatment. We gave antituberculous treatment for a total of 12 to 18 months in both groups and they were followed up for a mean of 30.2 months (24 to 49). A series of 20 healthy blood donors served as a control group.

Twenty-nine (93.6%) of the 31 patients in group I and 14 of the 20 (70%) in group II had a clinicoradiological healing response to treatment by five months.

The CD4 cell count in both groups was depressed at the time of enrolment, with a greater degree of depression in the group-II patients (686 cells/mm3 (sd 261) and 545 cells/mm3 (sd 137), respectively; p < 0.05). After treatment for three months both groups showed significant elevation of the CD4 cell count, reaching a level comparable with the control group. However, the mean CD4 cell count of group II (945 cells/mm3 (sd 343)) still remained lower than that of group I (1071 cells/mm3 (sd 290)), but the difference was not significant. Our study has shown encouraging results after immunomodulation and antituberculous treatment in non-responsive patients. The pattern of change in the CD4 cell count in response to treatment may be a reliable clinical indicator.

Influence of Bacillus Calmette-Guèrin vaccination at birth and 2 months old age on the peripheral blood T-cell subpopulations [gamma/delta and alpha-beta T cell]

The neonatal immune system is immature and may be affected by Bacillus Calmette-Guèrin (BCG) vaccine. We investigated the influence of BCG given at two different ages on the peripheral blood (PB) T-cell subpopulations. Forty full term healthy newborns were randomly chosen. Twenty of them were vaccinated with BCG at birth (group I) and the remaining at the age of 2 months (group II). The cell analysis were carried out before (pre-BCGI and pre-BCGII), and 2 months after (post-BCGI and post-BCGII) the vaccination. The analysis of the gamma/delta and alpha/beta T-cell receptor (TCR) antigens was done by two-colour flowcytometer. The purified protein derivative (PPD) response was investigated 2 months after vaccination. The results showed that although T-cell (TCR+ cell) counts showed no difference in PB before and after vaccination in both study groups, the total lymphocyte and non-T cell (TCR- cell) populations increased significantly whereas alphabetaT-cell population significantly decreased after vaccination. On the contrary, gammadeltaT-cell counts in PB increased significantly 2 months after vaccination in group I but not in group II. Total lymphocyte and non-T cell counts in vaccinated infants at 2 months of age (post-BCGI) were significantly higher than in unvaccinated infants of the same age whereas alphabetaT-cell count in vaccinated infants was significantly low. However, total T-cell and gammadeltaT-cell counts showed no difference. PPD positivity was similar in both study groups (61% in group I, 66% in group II). Neither alphabetaT- nor gammadeltaT-cell counts were different in PPD positive and PPD negative infants. Our study shows that BCG causes marked quantitative changes in the PB T-cell subpopulations in young infants.

Interferon-gamma and tumour necrosis factor-alpha production by CD4+ T and CD8+ T lymphocytes in AIDS patients with tuberculosis

Tuberculosis (TB) is usually more severe in HIV-infected patients, and the immune derangement found in co-infected patients may differ from that in each isolated disease. Following mitogen stimulation of peripheral blood mononuclear cells (PBMC), interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha production was evaluated in T cells by flow cytometry, and in culture supernatants by enzyme-linked immunosorbent assay (ELISA) in 33 individuals: 11 AIDS patients with tuberculosis, six asymptomatic HIV-1-infected patients, eight patients with tuberculosis and eight healthy controls. The proportion of CD4+ T lymphocytes expressing IFN-gamma did not differ between the groups, whereas a trend towards increased proportions of TNF-alpha-expression in CD4+ T cells was observed in the TB compared to the HIV group, while intermediate values were observed in co-infected patients. Detection of IFN-gamma and TNF-alpha in CD8+ T lymphocytes was higher in TB than in HIV individuals. Co-infected patients presented intermediate values for IFN-gamma, while TNF-alpha detection was similar to that in HIV mono-infection. In conclusion, the proportion of T cells expressing IFN-gamma was relatively preserved in co-infected patients compared to TB patients, while the percentage of T cells expressing TNF-alpha was decreased, mainly in CD8+ T lymphocytes. However, the marked reduction in T lymphocyte numbers in co-infected patients led to a striking reduction of both cytokines in PBMC supernatants, a finding that is consistent with the impaired response to Mycobacterium tuberculosis.

How to interpret and pursue an abnormal complete blood cell count in adults

A complete blood cell count (CBC) is one of the most common laboratory tests in medicine. For example, at our institution alone, approximately 1800 CBCs are ordered every day, and 10% to 20% of results are reported as abnormal. Therefore, it is in every clinician's interest to have some understanding of the specific test basics as well as a structured action plan when confronted with abnormal CBC results. In this article, we provide practical diagnostic algorithms that address frequently encountered conditions associated with CBC abnormalities including anemia, thrombocytopenia, leukopenia, polycythemia, thrombocytosis, and leukocytosis. The objective is to help the nonhematologist recognize when a subspecialty consultation is reasonable and when it may be circumvented, thus allowing a cost-effective and intellectually rewarding practice.

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.

Immunophenotypic characterization of peripheral T lymphocytes in Mycobacterium tuberculosis infection and disease

The cellular immune response probably plays a pivotal role in determining the clinical outcome after exposure to Mycobacterium tuberculosis. We used multi-parameter flow-cytometry to evaluate the distribution of T-lymphocyte subsets during infection and disease caused by M. tuberculosis. Samples were obtained from 71 volunteers to identify the T CD4+ and CD8+ lymphocyte numbers, and the activation plus memory/naïve phenotypes, as defined by CD38, HLA-DR, CD45RA and CD27 markers. Subjects were divided into 18 healthy volunteers without detectable reaction to purified protein derivative (PPD-), 18 health care workers with a recent conversion to PPD, 20 patients with active pulmonary tuberculosis (TBC) and 15 patients with treated TBC at 6 months of therapy. By multiple-comparison analyses, the T CD4+ lymphocyte number of the TBC group was lower than the PPD- group (P < 0.05). This difference was apparently lost after treatment. The higher and the lower number of naïve T CD4+ cells was observed in the PPD- and TBC group, respectively. CD8+ T lymphocytes were also statistically different among the four groups (P = 0.0002), lower in the TBC group (P < 0.05). CD8+ T lymphocyte activation was evaluated by the CD38 and HLA-DR surface expression. The percentage distribution of these markers was statistically different between the four groups (P = 0.0055). TBC patients had a higher percentage of CD38+ cells and mean fluorescence index, suggesting an overall increase of cell activation. These results suggest that peripheral T lymphocytes reflect cellular activation during TBC, along with possible redistribution of naïve, memory/effector and late differentiated memory/effector phenotypes in the peripheral blood after infection and disease caused by M. tuberculosis.

Alteration in CD29(high) CD4(+) lymphocyte subset is a common feature of early HIV disease and of active tuberculosis

Peripheral CD4 T-cell depletion has been observed in human immunodeficiency virus (HIV)-negative patients with pulmonary tuberculosis (TB). To investigate more accurately this alteration, we studied peripheral blood CD45RA(+) and CD29(high) CD4 subsets in 79 TB patients with (HIV(+)TB(+)) or without (HIV(-)TB(+)) HIV infection, 85 HIV-infected patients without TB (HIV(+)TB(-)), and 43 healthy controls, all living in West Africa. The high proportion of CD4(+)CD29(high) T cells observed in controls was dramatically decreased in CDC-A stage HIV(+)TB(-) patients. CD45RA(+) CD4(+) T cells were depleted during the CDC-B stage. Both the percentage and the absolute count of CD29(high)CD4(+) T cells were decreased in HIV(-)TB(+) and HIV(+)TB(+) patients versus controls, but CD45RA(+)CD4(+) T cells were not decreased in TB patients without HIV-infection. Although distinct alterations in the CD4(+) T-cell homeostasis are involved in TB(-) versus HIV-infected subjects, our data suggest that the CD29(+)CD4(+) T-cell depletion observed during the early HIV disease contributes to the risk of active TB, by reducing the pool of T cells able to relocalize to the sites of the M. tuberculosis multiplication.

Tuberculosis-associated severe CD4+ T-lymphocytopenia in HIV-seronegative patients from Dakar. SIDAK Research Group

OBJECTIVES

To determine the frequency and associated features of severe CD4+ T-lymphocytopenia (<300 cells/mm(3)) in HIV-seronegative patients with tuberculosis.

METHODS

Statistical analysis of 430 consecutively enrolled HIV-seronegative inpatients with tuberculosis in two teaching hospitals in Dakar, Senegal.

RESULTS

The mean CD4 + cell count was 602+/-318.3 cells/mm(3). CD4 + cell counts were below 300 cells/mm(3)in 62 patients (14.4%). Patients with fewer than 300 CD4+ cells/mm(3)differed from those with higher counts in being less likely to have a positive smear for acid-fast bacilli; in having a higher frequency of extrapulmonary involvement (pleural effusion, adenopathy and miliary disease) and oral candidiasis; and in having smaller tuberculin reactions, lower haemoglobin levels, less cavitation and less patchy infiltration. After adjustment for gender and age, all differences remained except miliary disease.

CONCLUSIONS

A substantial percentage (14.4%) of HIV-seronegative hospitalized patients for tuberculosis in a West African country presented with severe CD4 + T-lymphocyte depletion and had clinical and radiographic features indicative of more advanced disease and accompanying immunodepression. These results and those already published suggest that tuberculosis should be regarded as one of the diseases associated with a subgroup of patients with "idiopathic CD4 + T-lymphocytopenia".

Tuberculosis and human immunodeficiency virus infection

Mycobacterium tuberculosis infects one third of the world's population, and tuberculosis remains one of the most common infectious diseases of humans. From a global perspective, tuberculosis may be one of the most common HIV-related opportunistic infections. HIV immunosuppression has had a dramatic influence on the epidemiology, natural history and clinical presentation of tuberculosis. Treatment is highly effective for drug susceptible tuberculosis and has been shown to have a significant impact on resistant, especially multidrug-resistant, tuberculosis if started promptly. Directly observed therapy and rigorous adherence to infection control principles have helped control the tuberculosis epidemic in the United States.

Passive smoking and risk of pulmonary tuberculosis in children immediately following infection. A case-control study

SETTING

Passive smoking-related respiratory disorders in children.

OBJECTIVES

To assess the effect of passive smoking on the development of active pulmonary tuberculosis (PTB) in children immediately following infection by Mycobacterium tuberculosis within the family.

DESIGN

An unmatched case-control study in which 93 contacts who became cases (active PTB diagnosed) and 95 contacts who did not became cases (tuberculin-positive children without evidence of active disease) were included. All were household contacts of a new case of pulmonary bacillary tuberculosis. Smoking habits were investigated by a questionnaire. Urinary cotinine was analysed. Odds Ratio (OR) was adjusted for age and socio-economic status using multiple logistic regression analysis.

RESULTS

Passive smoking was a risk factor for PTB (OR: 5.29; 95% confidence interval (CI): 2.33-12.82; P < 0.00005). The adjusted OR was 5.39 (95% CI: 2.44-11.91; P < 0.00001). The risk increased when contacts were passive smokers both at home and outside the home within the family (OR: 6.35; 95% CI: 3.20, 12.72; P < 0.00001). Contacts 0-4 and 5-9 years old showed a significantly higher risk than those aged > or = 10. There was a dose-response relationship between the risk of developing active PTB immediately following infection and the number of cigarettes smoked daily by the household adults (P < 0.001). Mean (SD) urinary continine detectable concentrations (ng/ml) were different between disease contacts (119.46 [68.61]) and non diseased contacts (91.87 [73.10]). The difference was statistically significant (P < 0.001).

CONCLUSIONS

Passive exposure to tobacco smoke in children was associated with an increased risk of developing pulmonary tuberculosis immediately following infection. This is an association of great concern requiring health education programmes and antitobacco medical advice.

Haematological changes associated with miliary tuberculosis of the bone marrow

The peripheral blood and bone marrow findings in 25 patients found to have tuberculous granulomata on bone marrow examination were examined to determine whether specific haematological findings are associated with tuberculous infiltration of the bone marrow. All the patients had one abnormality or more on their full blood count. The presence of a peripheral lymphopaenia was the single factor common to all 25 patients studied. The peripheral lymphopaenia was only associated with bone marrow lymphopaenia in 14% of patients. Other findings of note were an association of peripheral monocytopaenia and absence of giant cells in the granulomata, and decreased iron stores in almost a third of the total number of patients. The relevance of the lymphopaenia, monocytopaenia and decreased iron stores are discussed and we propose that the absence of a peripheral lymphopaenia makes it very unlikely that there will be tuberculous localization in the bone marrow.