Increased synthesis of anti-tuberculous glycolipid immunoglobulin G (IgG) and IgA with cavity formation in patients with pulmonary tuberculosis

The coexistence of IgA vasculitis and tuberculosis: a case-based review

Immunoglobulin (Ig) A vasculitis (IgAV), formerly known as Henoch-Schonlein purpura (HSP), is a relatively uncommon form of vasculitis primarily targeting the skin, gastrointestinal system, and the kidneys. Although the pathogenesis has not yet been well identified, several triggering factors, such as infections, drugs, have been implicated in the development of IgAV. Tuberculosis (TB), albeit rare, may precipitate IgAV. Herein, we have presented a case manifested by purpuric skin rash and proteinuria 6 weeks following diagnosis of pulmonary tuberculosis while receiving anti-TB drugs. The case was diagnosed as having active tuberculosis and TB-related IgA vasculitis with multi-organ involvement. In this case-based review, we recruited cases with TB-related Ig A vasculitis from the literature and discussed the features of tuberculosis that mimic vasculitides and vice versa. We also discussed the difficulties in diagnosis and the therapeutic approach in the light of the literature.

Comparison of antibody responses against Mycobacterium tuberculosis antigen Rv0679c in tuberculosis patients from the endemic and non-endemic regions of the Beijing genotype: a case control study

Background

Strains of the Beijing genotype of Mycobacterium tuberculosis (MTB) are reportedly associated with the virulence of tuberculosis (TB) infection, unfavorable outcomes of anti-TB treatment, and the global TB pandemic. Rv0679c, a hypothetical membrane protein related to host cell invasion, has a Beijing genotype-specific mutation at residue 142 (Asn142Lys). Antigenicity differences between Rv0679c-Asn142 (N-type) and Rv0679c-Lys142 (K-type) have been previously observed in mice antigen-antibody responses. However, the immune response to Rv0679c in humans remains unknown. Therefore, we aimed to investigate the anti-Rv0679c immune response in TB patients from the endemic and non-endemic regions of the Beijing MTB genotype.

Methods

We analyzed the Rv0679c-specific antibody responses in 84 subjects from the endemic region of the Beijing genotype MTB in China, including 45 pulmonary TB patients (C-PTB) and 39 healthy controls (C-HC), and 81 subjects from the Philippines (the endemic region of the non-Beijing genotype), including 51 pulmonary TB patients (P-PTB) and 30 healthy controls (P-HC). Anti-tuberculous-glycolipid (TBGL) antigen was used as the control antibody.

Results

TBGL IgG titers were higher in both C-PTB and P-PTB than those in their corresponding HC (C-PTB median 4.2, P-PTB median 11.2; C-PTB vs. P-PTB, p > 0.05), suggesting immune response comparability in PTB from two different countries. C-PTB showed a higher response compared to C-HC for anti-K-type IgG (53.3%) than anti-N-type IgG (6.67%); this response was not observed in P-PTB (both N-type and K-type 9.80%).

Conclusion

Dimorphic antigen Rv0679c was found to be associated with distinct immune response patterns, indicating the role of Beijing/non-Beijing genotype of MTB in stimulating specific responses in TB patients from the endemic region of Beijing MTB. Meanwhile, reactions to Rv0679c in patients and HC from non-endemic regions of the Beijing MTB may be caused by the response to the common epitope of Rv0679c N/K-type.

Difference in Antibody Responses to Mycobacterium tuberculosis Antigens in Japanese Tuberculosis Patients Infected with the Beijing/Non-Beijing Genotype

The Beijing genotype Mycobacterium tuberculosis (MTB), notorious for its virulence and predisposition to relapse, could be identified by spoligotyping based on genetic heterogeneity. The plasma samples from 20 cases of Beijing and 16 cases of non-Beijing MTB infected individuals and 24 healthy controls (HCs) were collected, and antibodies against 11 antigens (Rv0679c142Asn, Rv0679c142Lys, Ag85B, Ag85A, ARC, TDM-M, TDM-K, HBHA, MDP-1, LAM, and TBGL) were measured by ELISA. Compared to the HCs, the MTB infected subjects showed higher titers of anti-Ag85B IgG (positivity 58.2%) and anti-ACR IgG (positivity 48.2%). Of note, anti-ACR IgG showed higher titer in Beijing MTB infected tuberculosis (TB) patients than in HC (Kruskal–Wallis test, p < 0.05), while the levels of anti-Ag85B, anti-TBGL, anti-TDM-K, and anti-TDM-M IgG were higher in non-Beijing TB patients than in HC. Moreover, anti-Ag85B IgG showed higher response in non-Beijing TB patients than in Beijing TB patients (p < 0.05; sensitivity, 76.9% versus 44.4%). The sensitivity and specificity analysis showed that 78.8% Beijing infected individuals were negative in anti-TBGL-IgG or/and anti-Ag85B-IgG, while 75.0% of those were positive in anti-TBGL-IgA or/and anti-ACR-IgG tests. These results indicate the possibility of developing antibody-based test to identify Beijing MTB.

Microchip-based ultrafast serodiagnostic assay for tuberculosis

Access to point-of-care (POC), rapid, inexpensive, sensitive, and instrument-free tests for the diagnosis of tuberculosis (TB) remains a major challenge. Here, we report a simple and low-cost microchip-based TB ELISA (MTBE) platform for the detection of anti-mycobacterial IgG in plasma samples in less than 15 minutes. The MTBE employs a flow-less, magnet-actuated, bead-based ELISA for simultaneous detection of IgG responses against multiple mycobacterial antigens. Anti-trehalose 6,6′-dimycolate (TDM) IgG responses were the strongest predictor for differentiating active tuberculosis (ATB) from healthy controls (HC) and latent tuberculosis infections (LTBI). The TDM-based MTBE demonstrated superior sensitivity compared to sputum microscopy (72% vs. 56%) with 80% and 63% positivity among smear-positive and smear-negative confirmed ATB samples, respectively. Receiver operating characteristic analysis indicated good accuracy for differentiating ATB from HC (AUC = 0.77). Thus, TDM-based MTBE can be potentially used as a screening device for rapid diagnosis of active TB at the POC.

Immunoglobulin G response to mammalian cell entry 1A (Mce1A) protein as biomarker of active tuberculosis

Cell wall components are major determinants of virulence of Mycobacterium tuberculosis and they contribute to the induction of both humoral and cell-mediated immune response. The mammalian cell entry protein 1A (Mce1A), in the cell wall of M. tuberculosis, mediates entry of the pathogen into mammalian cells. Here, we examined serum immunoglobulin levels (IgA, IgM and total IgG) against Mce1A as a potential biomarker for diagnosis and monitoring tuberculosis (TB) treatment response. Serum samples of 39 pulmonary TB patients and 65 controls (15 healthy household contacts, 19 latently infected household contacts, 13 non-TB and 18 leprosy patients) were screened by ELISA. The median levels of all immunoglobulin classes were significantly higher in TB patients when compared with control groups. The positive test results for IgA, IgM and total IgG were 62, 54 and 82%, respectively. For comparison, routine sputum smear examination diagnosed only 26 (67%) of 39 TB cases. Sensitivities of IgA, IgM and IgG test were 59, 51.3 and 79.5%, respectively, while the specificities observed were 77.3, 83.3 and 84.4%, respectively. A significant decrease compared with baseline was also shown after TB treatment. These results suggest that circulating total IgG antibody to Mce1A could be a complementary tool to diagnosis pulmonary TB.

Dynamic IgG antibody response to immunodominant antigens of M. tuberculosis for active TB diagnosis in high endemic settings

BACKGROUND

Even though various techniques have been developed for rapid diagnosis of tuberculosis (TB), still there is an immense need for a simple, cost effective, highly sensitive and specific test. Hence, one of the possibilities is identification of Mycobacterium tuberculosis specific antibodies in infected serum by using specific antigens.

METHODS

We tested 10 recombinant M. tuberculosis antigens to evaluate IgG levels among Healthy control subjects (HCS), Healthy household contacts (HHC) and pulmonary TB patients (PTB) by ELISA.

RESULTS

The median IgG levels specific to all the antigens are higher in PTB than HHC and HCS. Amongst single antigens, 38-kDa antigen has showed maximum sensitivity of 50% than any other antigens at 95.5% specificity. Among the two antigen combination, 38-kDa+Rv1860 has showed maximum sensitivity of 66.6% with specificity of 92.2%. The same antigen combination (38-kDa and Rv1860) predominantly identifies smear negative and culture positive TB patients with 68% sensitivity and 92.2% specificity. Most of the antigens have exhibited higher antibody titre in cavitary TB than non cavitary. With regard to latent TB infection (LTBI) identification, Rv1860 has exhibited maximum sensitivity of 53.3% with 95% specificity.

CONCLUSIONS

IgG response to combination of recombinant mycobacterial antigens (38-kDa, Rv1860, Rv2204c and Rv0753c) presents good specificity with acceptable level of sensitivity for TB diagnosis.

Evaluation of Anti-TBGL Antibody in the Diagnosis of Tuberculosis Patients in China

Tuberculous glycolipid (TBGL) is a component of the Mycobacterium tuberculosis cell wall, and anti-TBGL antibodies are used for serodiagnosis of tuberculosis. Anti-TBGL IgG and IgA levels were measured in 45 pulmonary TB patients (PTB), 26 extra-pulmonary TB patients (ETB), 16 AIDS-TB patients, and 58 healthy controls (HC) including 39 health care workers (HW) and 19 newly enrolled students (ST). Anti-TBGL IgG measurements yielded 68.9% and 46.2% sensitivity in PTB and ETB, respectively, and 81.0% specificity. However, anti-TBGL IgA measurements were significantly less sensitive in detecting ETB than PTB (15.4% versus 46.7% sensitivity) but showed up to 89.7% specificity. Samples from AIDS-TB patients exhibited low reaction of anti-TBGL IgG and IgA with 6.3% and 12.5% sensitivity, respectively. Unlike anti-lipoarabinomannan (LAM) IgG that was found to elevate in sputum smearpositive subjects, anti-TBGL IgG and IgA elevated in those with cavitation and bronchiectasis, respectively. Anti-TBGL IgG in cavitary TB yielded 78.2% sensitivity compared to 57.1% in those otherwise. Meanwhile, higher anti-TBGL IgA titers were observed in HW than in ST, and increasing anti-TBGL IgG titers were observed in HW on follow-up. Therefore, higher anti-TBGL antibody titers are present in patients presenting cavities and bronchiectasis and subjects under TB exposure risk.

Assessing humoral immune response of 4 recombinant antigens for serodiagnosis of tuberculosis

Serodiagnostic potential of four recombinant proteins (38 kDa[Rv0934], MPT64[Rv1980c], Adk[Rv0733], and BfrB[Rv3874]) was evaluated in Healthy control subjects (HCS), Healthy household contacts (HHC), Pulmonary tuberculosis patients (PTB), and Human immuno deficiency virus & Tuberculosis co-infected patients (HIV-TB). All the antigens tested individually for the detection of serum IgG by indirect ELISA. All the four antigens have a significantly higher antibody response in PTB compared to healthy controls (P < 0.05). The sensitivity of individual antigens ranged from 20% to 52.5% for the prefixed specificity of 95%. When results of all 4 antigens were combined the sensitivity was increased to 75% and specificity was reduced 89% in HCS. In smear- and culture-positive (S+C+) PTB, four antigen combination gives maximum sensitivity (89.6%) with 89% specificity. In smear negative culture negative (S-C+) PTB, three antigen combination (38 kDa with MPT64 and BfrB) gives maximum sensitivity (69.5%) and specificity (91.6%). In HIV-TB, 4 antigen combinations give the maximum sensitivity of 51.2% with 89% specificity. Combining serology (Four antigen combination) with smear was able to increase the sensitivity from 70% to 92.5% in culture positive PTB. So, we propose that this serology test can be used as adjunct test along with smear for rapid diagnosis of PTB.

Diagnostic value of antibody responses to multiple antigens from Mycobacterium tuberculosis in active and latent tuberculosis

We investigated the antibody responses to 10 prospective Mycobacterium tuberculosis (MTB) antigens and evaluated their ability to discriminate between latent (LTBI) and active pulmonary tuberculosis (TB). Our results indicate that plasma levels of anti-α-crystallin (ACR), antilipoarabinomannan, anti-trehalose 6,6'-dimycolate, and anti-tubercular-glycolipid antigen antibodies were higher in patients with active TB, compared to those in the LTBI and control subjects. No differences in the antibodies were observed between the control and LTBI subjects. Antibodies against the glycolipid antigens could not distinguish between Mycobacterium avium complex (MAC)-negative TB patients and MAC-infected LTBI individuals. The most useful serological marker was antibodies to ACR, with MAC-negative TB patients having higher titers than those observed in MAC-positive LTBI and control subjects. Our data indicate that antibody to ACR is a promising target for the serological diagnosis of patients with active TB patients. When dealing with antiglycolipid antibodies, MAC coinfection should always be considered in serological studies.

IgG, IgM and IgA antibodies against the novel polyprotein in active tuberculosis

BACKGROUND

The present study was aimed to evaluate whether IgG, IgM and IgA antibodies levels detected against a novel Mycobacterium tuberculosis polyprotein 38 F-64 F (with 38 F being the abbreviation for 38kD-ESAT6-CFP10 and 64 F for Mtb8.4-MPT64-TB16.3-Mtb8) are suitable for diagnosing active tuberculosis, and for monitoring the efficacy of chemotherapy on TB patients.

METHODS

In this study, a total of 371 active TB patients without treatment were selected and categorized into S+/C+group (n=143), S-/C+group (n=106) or S-/C- group (n=122). A series of serum samples were collected from 82 active TB patients who had undergone anti-TB chemotherapy for 0-6 months at one month interval. Humoral responses (IgG, IgM and IgA) were determined for the novel Mycobacterium tuberculosis polyprotein using indirect ELISA methods in all of serum samples.

RESULTS

For S+/C+, S-/C+and S-/C- active tuberculosis patients before anti-TB chemotherapy, the sensitivities of tests based on IgG were 65.7%, 46.2% and 52.5% respectively; the sensitivities based on IgM were 21.7%, 24.5% and 18.9%; and the sensitivities based on IgA were 25.2%, 17.9% and 23.8%. By combination of three isotypes, for all active tuberculosis patients, the test sensitivity increased to 70.4% with the specificity being 91.5%. After anti-TB chemotherapy, there were no significant differences between groups with different courses of anti-TB chemotherapy.

CONCLUSIONS

The novel Mycobacterium tuberculosis polyprotein 38 F-64 F represents potential antigen suitable for measuring IgG, IgM and IgA antibodies. However, the serodiagnostic test based on the 38 F-64 F polyprotein appears unsuitable for monitoring the efficacy of chemotherapy.

IgG, IgM and IgA antibodies against the novel polyprotein in active tuberculosis

BACKGROUND

The present study was aimed to evaluate whether IgG, IgM and IgA antibodies levels detected against a novel Mycobacterium tuberculosis polyprotein 38 F-64 F (with 38 F being the abbreviation for 38kD-ESAT6-CFP10 and 64 F for Mtb8.4-MPT64-TB16.3-Mtb8) are suitable for diagnosing active tuberculosis, and for monitoring the efficacy of chemotherapy on TB patients.

METHODS

In this study, a total of 371 active TB patients without treatment were selected and categorized into S+/C+group (n=143), S-/C+group (n=106) or S-/C- group (n=122). A series of serum samples were collected from 82 active TB patients who had undergone anti-TB chemotherapy for 0-6 months at one month interval. Humoral responses (IgG, IgM and IgA) were determined for the novel Mycobacterium tuberculosis polyprotein using indirect ELISA methods in all of serum samples.

RESULTS

For S+/C+, S-/C+and S-/C- active tuberculosis patients before anti-TB chemotherapy, the sensitivities of tests based on IgG were 65.7%, 46.2% and 52.5% respectively; the sensitivities based on IgM were 21.7%, 24.5% and 18.9%; and the sensitivities based on IgA were 25.2%, 17.9% and 23.8%. By combination of three isotypes, for all active tuberculosis patients, the test sensitivity increased to 70.4% with the specificity being 91.5%. After anti-TB chemotherapy, there were no significant differences between groups with different courses of anti-TB chemotherapy.

CONCLUSIONS

The novel Mycobacterium tuberculosis polyprotein 38 F-64 F represents potential antigen suitable for measuring IgG, IgM and IgA antibodies. However, the serodiagnostic test based on the 38 F-64 F polyprotein appears unsuitable for monitoring the efficacy of chemotherapy.

Correlating interleukin-12 stimulated interferon-γ production and the absence of ectodermal dysplasia and anhidrosis (EDA) in patients with mutations in NF-κB essential modulator (NEMO)

OBJECTIVE

Patients with hypomorphic mutations in Nuclear Factor-κB Essential Modulator (NEMO) are immunodeficient (ID) and most display ectodermal dysplasia and anhidrosis (EDA). We compared cytokine production by NEMO-ID patients with and without EDA.

METHODS

PBMCs of NEMO-ID patients, four with EDA carrying E315A, C417R, D311N and Q403X, and three without EDA carrying E315A, E311_L333del and R254G, were cultured with PHA, PHA plus IL-12p70, LPS, LPS plus IFN-γ, TNF and IL-1β. The production of various cytokines was measured in the supernatants. Fifty-nine healthy individuals served as controls.

RESULTS

PBMCs of NEMO-ID patients without EDA produce subnormal amounts of IFN-γ after stimulation with PHA, but normal amounts of IFN-γ after PHA plus IL-12p70. In contrast, IFN-γ production by patients with EDA was low in both cases. Patients with EDA also generate lower PHA-stimulated IL-10 and IL-1β than controls, whereas the production of these cytokines by patients without EDA was normal.

CONCLUSION

Responses of PBMCs in NEMO-ID patients with EDA to PHA with and without IL-12p70 appear less robust than in NEMO-ID patients without EDA. This possibly indicates a better preserved NEMO function in our patients without EDA.

Utility of host markers detected in Quantiferon supernatants for the diagnosis of tuberculosis in children in a high-burden setting

Background

The diagnosis of childhood tuberculosis (TB) disease remains a challenge especially in young and HIV-infected children. Recent studies have identified potential host markers which, when measured in Quantiferon (QFT-IT) supernatants, show promise in discriminating between Mycobacterium tuberculosis (M.tb) infection states. In this study, the utility of such markers was investigated in children screened for TB in a setting with high TB incidence.

Methodology and Principal Findings

76 children (29% HIV-infected) with or without active TB provided blood specimens collected directly into QFT-IT tubes. After overnight incubation, culture supernatants were harvested, aliquoted and frozen for future immunological research purposes. Subsequently, the levels of 12 host markers previously identified as potential TB diagnostic markers were evaluated in these supernatants for their ability to discriminate between M.tb infection and disease states using the Luminex platform. Of the 76 children included, 19 (25%) had culture confirmed TB disease; 26 (46%) of the 57 without TB had positive markers of M.tb infection defined by a positive QFT-IT test. The potentially most useful analytes for diagnosing TB disease included IFN-α2, IL-1Ra, sCD40L and VEGF and the most useful markers for discriminating between QFT-IT positive children as TB or latent infection included IL-1Ra, IP-10 and VEGF. When markers were used in combinations of four, 84% of all children were accurately classified into their respective groups (TB disease or no TB), after leave-one-out cross validation.

Conclusions

Measurement of the levels of IFN-α2, IL-1Ra, sCD40L, IP-10 and VEGF in QFT-IT supernatants may be a useful method for diagnosing TB disease and differentiating between active TB disease and M.tb infection in children. Our observations warrant further investigation in larger well-characterized clinical cohorts.

Distinct clinical features in nontuberculous mycobacterial disease with or without latent tuberculosis infection

Nontuberculous mycobacteria (NTM) diseases are in the face of a progressive increase even in immune-competent subjects, and the clinical features of NTM diseases are heterogenous. The decision to institute treatment of the patients should be made after a period of follow up, because therapy is often prolonged, and frequently ineffective. The reasons why some patients develop severe NTM diseases are not clear. Here we observed the involvement of latent tuberculosis infection (LTBI) in clinical and laboratory features of NTM diseases. We evaluated various tuberculosis-related inflammatory markers including osteopontin (OPN), pentraxin-3 (PTX-3), and soluble IL-2 receptor (sIL-2R) in NTM infected patients with or without LTBI. Eight NTM and 5 tuberculosis (TB) patients, and 5 healthy subjects were enrolled. Polymerase Chain Reaction (PCR) analysis confirmed the absence of tuberculosis specific gene (RD1 region), among clinical isolates from NTM patients. Interferon-γ (IFN-γ) release assay (IGRA) using Early Secreted Antigenic Target-6 (ESAT-6) and CFP-10, the RD1-encoded protein, was employed for determining LTBI. IGRA was positive in 4/8 NTM (NTM with LTBI, 50%) and 5/5 TB patients. Only 2 of 4 NTM with LTBI were under chemotherapy among all NTM patients, and others were followed up. The plasma levels of OPN, PTX3 and sIL-2R were significantly higher in NTM patients with LTBI than in those without LTBI (P < 0.05). The two patients under therapy showed the highest OPN levels that persisted after treatment. The increased inflammatory levels in NTM patients with LTBI indicate enhanced inflammatory reaction. Extensive therapy may be necessary in such patients.

Frequent detection of anti-tubercular-glycolipid-IgG and -IgA antibodies in healthcare workers with latent tuberculosis infection in the Philippines

Anti-tubercular-glycolipid-IgG (TBGL-IgG) and -IgA (TBGL-IgA) antibodies, and the QuantiFERON-TB Gold test (QFT) were compared in healthcare workers (HCWs, n = 31) and asymptomatic human immunodeficiency virus-carriers (HIV-AC, n = 56) in Manila. In HCWs, 48%, 51%, and 19% were positive in QFT, TBGL-IgG, and -IgA, respectively. The TBGL-IgG positivity was significantly higher (P = 0.02) in QFT-positive than QFT-negative HCWs. Both TBGL-IgG- and -IgA-positive cases were only found in QFT-positive HCWs (27%). The plasma IFN-γ levels positively correlated with TBGL-IgA titers (r = 0.74, P = 0.005), but not TBGL-IgG titers in this group, indicating that mucosal immunity is involved in LTBI in immunocompetent individuals. The QFT positivity in HIV-AC was 31% in those with CD4+ cell counts >350/μL and 12.5% in low CD4 group (<350/μL). 59 % and 29% were positive for TBGL-IgG and -IgA, respectively, in HIV-AC, but no association was found between QFT and TBGL assays. TBGL-IgG-positive rates in QFT-positive and QFT-negative HIV-AC were 61% and 58%, and those of TBGL-IgA were 23% and 30%, respectively. The titers of TBGL-IgA were associated with serum IgA (P = 0.02) in HIV-AC. Elevations of TBGL-IgG and -IgA were related to latent tuberculosis infection in HCWs, but careful interpretation is necessary in HIV-AC.

Antituberculosis IgG antibodies as a marker of active Mycobacterium tuberculosis disease

Anti-Mycobacterium tuberculosis IgG antibodies may aid in the diagnosis of active M. tuberculosis disease. We studied whether anti-M. tuberculosis IgG antibodies are elevated in active M. tuberculosis disease and assessed factors contributing to false-positive and -negative results. A retrospective study of 2,150 individuals tested by the QuantiFERON-TB Gold In-Tube (QFT-GIT) assay was conducted at the University of Utah, ARUP Laboratories, November 2008 to December 2010. All samples were tested with the InBios Active TbDetect antituberculosis (anti-TB) IgG antibody assay. Of 1,044 patients with a positive QFT-GIT, 59 (5.7%) were positive for M. tuberculosis antibodies. Fourteen of 1,106 (1.3%) with a negative or indeterminate QFT-GIT were positive for M. tuberculosis antibodies. M. tuberculosis antibody tests were positive in 61.5% with confirmed active M. tuberculosis disease and other mycobacterial infections. Over half of the false-negative M. tuberculosis antibody tests occurred in patients ≥ 90 years of age. False positives were seen in 12.9% of autoimmune patients. The odds ratio of being positive by the QFT-GIT and the InBios TB IgG assay increased with confirmed M. tuberculosis disease or highly suspected M. tuberculosis disease and was 86.7 (95% confidence interval [CI], 34.4 to 218.5) in these two groups compared to patients negative by both tests. Although anti-M. tuberculosis antibodies can be detected in patients with active M. tuberculosis disease, caution should be used with patients where immunoglobulin levels may be decreased or patients with autoantibodies.

Commercial serological tests for the diagnosis of active pulmonary and extrapulmonary tuberculosis: an updated systematic review and meta-analysis

BACKGROUND

Serological (antibody detection) tests for tuberculosis (TB) are widely used in developing countries. As part of a World Health Organization policy process, we performed an updated systematic review to assess the diagnostic accuracy of commercial serological tests for pulmonary and extrapulmonary TB with a focus on the relevance of these tests in low- and middle-income countries.

METHODS AND FINDINGS

We used methods recommended by the Cochrane Collaboration and GRADE approach for rating quality of evidence. In a previous review, we searched multiple databases for papers published from 1 January 1990 to 30 May 2006, and in this update, we add additional papers published from that period until 29 June 2010. We prespecified subgroups to address heterogeneity and summarized test performance using bivariate random effects meta-analysis. For pulmonary TB, we included 67 studies (48% from low- and middle-income countries) with 5,147 participants. For all tests, estimates were variable for sensitivity (0% to 100%) and specificity (31% to 100%). For anda-TB IgG, the only test with enough studies for meta-analysis, pooled sensitivity was 76% (95% CI 63%-87%) in smear-positive (seven studies) and 59% (95% CI 10%-96%) in smear-negative (four studies) patients; pooled specificities were 92% (95% CI 74%-98%) and 91% (95% CI 79%-96%), respectively. Compared with ELISA (pooled sensitivity 60% [95% CI 6%-65%]; pooled specificity 98% [95% CI 96%-99%]), immunochromatographic tests yielded lower pooled sensitivity (53%, 95% CI 42%-64%) and comparable pooled specificity (98%, 95% CI 94%-99%). For extrapulmonary TB, we included 25 studies (40% from low- and middle-income countries) with 1,809 participants. For all tests, estimates were variable for sensitivity (0% to 100%) and specificity (59% to 100%). Overall, quality of evidence was graded very low for studies of pulmonary and extrapulmonary TB.

CONCLUSIONS

Despite expansion of the literature since 2006, commercial serological tests continue to produce inconsistent and imprecise estimates of sensitivity and specificity. Quality of evidence remains very low. These data informed a recently published World Health Organization policy statement against serological tests. Please see later in the article for the Editors' Summary.

Serum prolidase activity in patients with pulmonary tuberculosis

AIM

To investigate serum prolidase activity (SPA) in patients with pulmonary tuberculosis (PTB).

MATERIAL AND METHODS

Twenty-nine PTB patients and 32 controls were included in the study. PTB patients (cavitary and non-cavitary) and controls were compared in terms of mean SPA. Correlations were evaluated between SPA and acute phase reactants.

RESULTS

Mean SPA was significantly higher in PTB patients than in the control group. Mean SPA was significantly higher in patients with cavitary TB than non-cavitary TB. Mean SPA in patients with mild PTB was lower than patients with moderate and severe disease. We found significant correlations between SPA and CRP, ESR, albumin, platelet counts, HDL-cholesterol and LDH activity.

CONCLUSION

This study has shown that PTB patients have higher SPA than controls. The increase in SPA might be related to tissue destruction, increased immunoglobulin, complement levels and increased fibroblastic activity; all of which are involved in the natural history of PTB.

Association between serum soluble CD40 ligand levels and mortality in patients with severe sepsis

INTRODUCTION

CD40 Ligand (CD40L) and its soluble counterpart (sCD40L) are proteins that exhibit prothrombotic and proinflammatory properties on binding to their cell surface receptor CD40. The results of small clinical studies suggest that sCD40L levels could play a role in sepsis; however, there are no data on the association between sCD40L levels and mortality of septic patients. Thus, the aim of this study was to determine whether circulating sCD40L levels could be a marker of adverse outcome in a large cohort of patients with severe sepsis.

METHODS

This was a multicenter, observational and prospective study carried out in six Spanish intensive care units. Serum levels of sCD40L, tumour necrosis factor-alpha and interleukin-10, and plasma levels of tissue factor were measured in 186 patients with severe sepsis at the time of diagnosis. Serum sCD40L was also measured in 50 age- and sex-matched controls. Survival at 30 days was used as the endpoint.

RESULTS

Circulating sCD40L levels were significantly higher in septic patients than in controls (P = 0.01), and in non-survivors (n = 62) compared to survivors (n = 124) (P = 0.04). However, the levels of CD40L were not different regarding sepsis severity. Logistic regression analysis showed that sCD40L levels >3.5 ng/mL were associated with higher mortality at 30 days (odds ratio = 2.89; 95% confidence interval = 1.37 to 6.07; P = 0.005). The area under the curve of sCD40L levels >3.5 ng/mL as predictor of mortality at 30 days was 0.58 (95% CI = 0.51 to 0.65; P = 0.03).

CONCLUSIONS

In conclusion, circulating sCD40L levels are increased in septic patients and are independently associated with mortality in these patients; thus, its modulation could represent an attractive therapeutic target.

[Immunodiagnosis and biomarkers in tuberculosis]

Based on the tuberculin skin test it is estimated that latent tuberculosis infection is present in one-third of the world's population. The new strategies in public health and research are aimed to reduce and eradicate this enormous reservoir. However, the absence of effective biomarkers for diagnosis and treatment of latent tuberculosis limits the development of new drugs and vaccines. Some components are present in both, the PPD (used in the tuberculin skin test) and the BCG vaccine. This increases the number of false positives in vaccinated individuals. Nowadays, there is not an immune diagnostic method that can differentiate latent tuberculosis and tuberculosis disease. New studies have addressed some strategies including specific antibodies, new cytokines and / or antigens as candidates for biomarkers. However, the high costs of these studies, the low number of participants and their different methodology make difficult a future meta-analysis and more conclusive results.

Host markers in QuantiFERON supernatants differentiate active TB from latent TB infection: preliminary report

Background

Interferon gamma release assays, including the QuantiFERON^® TB Gold In Tube (QFT) have been shown to be accurate in diagnosing Mycobacterium tuberculosis infection. These assays however, do not discriminate between latent TB infection (LTBI) and active TB disease.

Methods

We recruited twenty-three pulmonary TB patients and 34 household contacts from Cape Town, South Africa and performed the QFT test. To investigate the ability of new host markers to differentiate between LTBI and active TB, levels of 29 biomarkers in QFT supernatants were evaluated using a Luminex multiplex cytokine assay.

Results

Eight out of 29 biomarkers distinguished active TB from LTBI in a pilot study. Baseline levels of epidermal growth factor (EGF) soluble CD40 ligand (sCD40L), antigen stimulated levels of EGF, and the background corrected antigen stimulated levels of EGF and macrophage inflammatory protein (MIP)-1β were the most informative single markers for differentiation between TB disease and LTBI, with AUCs of 0.88, 0.84, 0.87, 0.90 and 0.79 respectively. The combination of EGF and MIP-1β predicted 96% of active TB cases and 92% of LTBIs. Combinations between EGF, sCD40L, VEGF, TGF-α and IL-1α also showed potential to differentiate between TB infection states. EGF, VEGF, TGF-α and sCD40L levels were higher in TB patients.

Conclusion

These preliminary data suggest that active TB may be accurately differentiated from LTBI utilizing adaptations of the commercial QFT test that includes measurement of EGF, sCD40L, MIP-1β, VEGF, TGF-α or IL-1α in supernatants from QFT assays. This approach holds promise for development as a rapid diagnostic test for active TB.