BACKGROUND: Accurate diagnosis of TB infection (TBI) is challenging due to the lack of a gold standard. Tuberculin skin test (TST) and interferon-gamma release assay (IGRA) are currently useful in ...TBI diagnosis, but both have several limitations. This study aims to evaluate inter-operator
variability in TST measurements and determine its impact on TBI diagnosis and treatment.METHODS: This was a retrospective analysis of patients screened for TBI using at least TST at a public outpatient clinic specialised in TB from January 2019 to August 2021. TST readings performed
by five experienced nurses were compared.RESULTS: A total of 671 screenings were analysed. TST positivity rate (P < 0.001) and mean TST measurements obtained by our nurses were significantly different (P < 0.001). Concordance of TST and IGRA results was of 83.4%
in the overall population (κ = 0.479). However, TST/IGRA agreement was significantly different among nurses (P = 0.003).CONCLUSION: Our analysis of TST measurements by experienced nurses shows significant differences in TST positivity rate, mean measured values and
overall concordance with IGRA. This led to significant different outcomes in TBI diagnosis and subsequent treatment. TST measurement differences could potentially be more pronounced if we considered untrained operators or those with occasional reading experience.
Introduction: Latent tuberculosis infection (LTBI) accounts for almost a quarter of the world population, and, in 5-10% of the subjects with impaired immune-response against M. tuberculosis growth, ...it may progress to active tuberculosis (TB). In this review, we focus on the need to propose a screening for LTBI including preventive therapy offer in rheumatic patients undergoing therapy with biological drugs.
Areas covered: We report on evidence that biologics are associated with an increased risk of active TB reactivation. This effect seems to be mainly limited to treatment with anti-tumor necrosis factor (TNF) agents, while non-anti-TNF-targeted biologics are not likely associated to any increased risk. We introduce the concept that the patients' coexisting host-related risk factors, such as comorbidities, are crucial to identify those at higher risk to reactivate TB. We report that preventive TB therapy is well tolerated in patients treated with biological drugs.
Expert commentary: Availability of non-anti-TNF targeted biologics, that are not associated with an increased risk of TB reactivation, offers a great opportunity to tailor a therapeutic intervention at low/absent TB risk. After proper LTBI screening investigations, preventive TB therapy has been demonstrated to be effective and well-tolerated to reduce the risk of TB reactivation in rheumatic patients requiring biological drugs.
Abstract
Background
We measured T-cell and antibody responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vaccinated patients hospitalized for coronavirus disease 2019 ...(COVID-19) and explored their potential value to predict outcomes.
Methods
This was a prospective, longitudinal study including vaccinated patients hospitalized with Delta and Omicron SARS-CoV-2 variants. TrimericS-IgG antibodies and SARS-CoV-2 T-cell response were measured using a specific quantitative interferon-γ release assay (IGRA). Primary outcome was all-cause 28-day mortality or need for intensive care unit (ICU) admission. Cox models were used to assess associations with outcomes.
Results
Of 181 individuals, 158 (87.3%) had detectable SARS-CoV-2 antibodies, 92 (50.8%) showed SARS-CoV-2–specific T-cell responses, and 87 (48.1%) had both responses. Patients who died within 28 days or were admitted to ICU were less likely to have both unspecific and specific T-cell responses in IGRA. In adjusted analyses (adjusted hazard ratio 95% confidence interval), for the entire cohort, having both T-cell and antibody responses at admission (0.16 .05–.58) and Omicron variant (0.38 .17–.87) reduced the hazard of 28-day mortality or ICU admission, whereas higher Charlson comorbidity index score (1.27 1.07–1.51) and lower oxygen saturation to fraction of inspired oxygen ratio (2.36 1.51–3.67) increased the risk.
Conclusions
Preexisting immunity against SARS-CoV-2 is strongly associated with patient outcomes in vaccinated individuals requiring hospital admission for COVID-19. Persons showing both T-cell and antibody responses have the lowest risk of severe outcomes.
In this prospective study of vaccinated patients hospitalized for COVID-19, T-cell immunity against SARS-CoV-2 measured by interferon-γ release assay (IGRA) was strongly associated with patient outcomes. Persons showing both positive antibody test and T-cell responses by IGRA had the lowest risk of mortality.
•TSPOT.COVID is an ELISpot interferon gamma-release assay for SARS-CoV-2•TSPOT.COVID identifies a T cell response to SARS-CoV-2 spike S1 and N peptides•2–8 weeks post SARS-CoV-2 diagnosis TSPOT.COVID ...detected 98% of infections•In comparison, immunoglobulin G (IgG) serology detected 83% of infections in the same period•Cellular immune response activated sooner and lasted longer than antibodies
To evaluate the performance of the T-SPOT.COVID test for identifying SARS-CoV-2-responsive T-cells in participants with SARS-CoV-2 infection.
The T-SPOT.COVID test uses ELISpot interferon-gamma release assay (IGRA) methodology to measure T cell responses to SARS-CoV-2 spike S1 and nucleocapsid peptides. T-SPOT.COVID and anti-N immunoglobulin (Ig) G serology tests were performed on blood from 186 patients with nucleic acid amplification test (NAAT)-confirmed-SARS-CoV-2 infection and 100 control group participants.
In the 2–8 weeks after NAAT-diagnosed SARS-CoV-2 infection, the T-SPOT.COVID test detected 98.4% (63 of 64) of infected participants, while anti-N IgG serology detected 82.8%. In the first 2 weeks after diagnosis, during adaptive immune response activation, there were less reactive T-SPOT.COVID responses (75.7%, 28 of 37 infected participants) and many less seropositive responses (32.4%). Response numbers tapered after 8 weeks; however, T-SPOT.COVID test continued to detect most participants with confirmed infection (83.6%, 56 of 67) and continued to out-perform serology (52.2%). T-SPOT.COVID response due to cross-reactive T cells was ruled out by demonstrating that, of 44 control group participants with T cells responsive to 4 human common cold coronavirus peptides, only 1 was T-SPOT.COVID reactive.
The T-SPOT.COVID test performed well in detecting SARS-CoV-2-sensitized T-cells over many months.
Immunosuppression induced by
is important in the pathogenesis of active tuberculosis (TB). However, the impact of depressed TB-specific and non-TB-specific gamma interferon (IFN-γ) response on the ...treatment outcomes of TB patients remains uncertain. In this prospective cohort study, culture- or pathology-proven active TB patients were enrolled and QuantiFERON-TB Gold In-Tube (QFT-GIT) assays were performed before the initiation of anti-TB treatment. TB-specific IFN-γ responses (TB antigen tube subtracted from the nil tube) and non-TB-specific IFN-γ responses (mitogen tube subtracted from the nil tube) were measured and associated with treatment outcomes, including 2-month culture conversion and on-treatment mortality. A total of 212 active TB patients were included in the analysis. We observed a close correlation between decreased lymphocyte count and lower non-TB-specific IFN-γ responses but not TB-specific IFN-γ responses. Patients with lower non-TB-specific IFN-γ responses had lower 2-month culture conversion rate (71.1% versus 84.7%, respectively;
= 0.033) and higher on-treatment mortality (22.6% versus 5.7%, respectively;
= 0.001) than those with higher non-TB-specific IFN-γ responses. In multivariate analysis, depressed non-TB-specific IFN-γ response was an independent factor associated with 2-month sputum culture nonconversion (odds ratio OR, 2.49; 95% CI 95% confidence interval, 1.05 to 5.90) and on-treatment mortality (hazard ratio HR, 2.76; 95% CI, 1.15 to 6.62). In contrast, depressed TB-specific IFN-γ responses were significantly associated with higher on-treatment mortality in univariate analysis but not in multivariate analysis. Our findings suggest that depressed non-TB-specific responses, but not TB-specific IFN-γ responses, as measured by QFT-GIT before the initiation of anti-TB treatment, were significantly associated with worse treatment outcomes in TB patients.
The immune response is a dynamic system that maintains the integrity of the body, and more specifically fight against infections. However, an unbalanced host immune response is highlighted in many ...diseases. Exacerbated responses lead to autoimmune and allergic diseases, whereas, low or inefficient responses favor opportunistic infections and viral reactivations. Conflicting situations may also occur, such as in sepsis where inflammation and compensatory immunosuppression make it difficult to deploy the appropriate drug treatment. Until the current day, assessing the immune profile of patients remains a challenge. This is especially due to the inter-individual variability-a key feature of the immune system-which hinders precise diagnosis, prognosis, and therapeutic stratification. Our incapacity to practically interpret the host response may contribute to a high morbidity and mortality, such as the annual 6 million worldwide deaths in sepsis alone. Therefore, there is a high and increasing demand to assess patient immune function in routine clinical practice, currently met by Immune Functional Assays. Immune Functional Assays (IFA) hold a plethora of potentials that include the precise diagnosis of infections, as well as prediction of secondary and latent infections. Current available products are devoted to indirect pathogen detection such as Mycobacteria tuberculosis interferon gamma release assays (IGRA). In addition, identifying the status and the underlying factors of immune dysfunction (e.g., in septic patients) may guide immune targeted therapies. Tools to monitor and stratify the immune status are currently being studied but they still have many limitations such as technical standardization, biomarkers relevance, systematic interpretation and need to be simplified, in order to set the boundaries of "healthy," "ill," and "critically ill" responses. Thus, the design of new tools that give a comprehensive insight into the immune functionality, at the bedside, and in a timely manner represents a leap toward immunoprofiling of patients.
•Mycobacterium tuberculosis (Mtb) DNA is detected in the peripheral blood cells of donors with tuberculosis (TB) or TB infection.•Mtb DNA is detected in the peripheral blood cells of donors with ...presumptive TB.•Mtb DNA detection is more frequent in peripheral CD34+ cells.•CD34+ cells may represent a niche for Mtb.•Mtb DNA in peripheral blood cells may be a new microbial biomarker.
To investigate whether Mycobacterium tuberculosis (Mtb) DNA is detected in peripheral blood mononuclear cells (PBMC) of subjects with tuberculosis (TB) or TB infection (TBI) living in a low-burden country.
We prospectively enrolled 57 patients with TB, 41 subjects with TBI, and 39 controls in Rome, Italy. PBMC were isolated, cluster of differentiation (CD)34+ and CD34− cells were immunomagnetic separated, DNA was extracted, and digital polymerase chain reaction for IS6110 and rpoB sequences was used to detect Mtb DNA in PBMC subsets and unfractionated PBMC.
We detected Mtb DNA at a low copy number in CD34+ cells in 4o f 30 (13%) patients with TB, 2 of 24 (8%) subjects with TBI, and 1 of 24 (4%) controls. Mtb DNA was detected in unfractionated PBMC in 3 of 51 (6%) patients with TB, 2 of 38 (5%) subjects with TBI, and 2 of 36 (6%) controls. In CD34− cells, only 1 of 31 (3%) subjects with TBI tested positive for Mtb DNA.
Mtb DNA was detected at low frequencies and levels in the PBMC of subjects with TBI and donors with TB living in a low-burden country. In particular, Mtb DNA was detected more frequently in CD34+ cells, supporting the hypothesis that these cells may represent a Mtb niche. This finding informs biological understanding of Mtb pathogenesis and may support the development of a microbial blood biomarker for Mtb infection.
Interferon-gamma release assays (IGRAs) that measure pathogen-specific T-cell response rates can provide a more reliable estimate of protection than specific antibody levels but have limited ...potential for widespread use due to their workflow, personnel, and instrumentation demands. The major vaccines for SARS-CoV-2 have demonstrated substantial efficacy against all of its current variants, but approaches are needed to determine how these vaccines will perform against future variants, as they arise, to inform vaccine and public health policies. Here we describe a rapid, sensitive, nanolayer polylysine-integrated microfluidic chip IGRA read by a fluorescent microscope that has a 5 h sample-to-answer time and uses ∼25 μL of a fingerstick whole blood sample. Results from this assay correlated with those of a comparable clinical IGRA when used to evaluate the T-cell response to SARS-CoV-2 peptides in a population of vaccinated and/or infected individuals. Notably, this streamlined and inexpensive assay is suitable for high-throughput analyses in resource-limited settings for other infectious diseases.
Interferon gamma release assay (IGRA) is used to detect latent tuberculosis prior to biological treatments in the context of suspected inflammatory rheumatism.
We report the case of a 50-year-old ...woman with negative IGRA test before adalimumab introduction for presumed axial spondyloarthritis.
The worsening of symptoms under treatment led to further investigations and the diagnostic of disseminated tuberculosis (TB) was later established with miliary and multiple bone locations such as spondylitis and sacroilitis. The patient's history revealed past exposure to tuberculosis. This observation illustrates the limitations of IGRA in such situation due to its variable performance for active TB diagnosis.
Misdiagnosis is frequent in bone tuberculosis due to non-specific signs. We draw the attention to the importance of a global risk assessment prior to the introduction of biological treatment for suspected chronic inflammatory rheumatism and recall the risk factors for false-negative IGRA. An extended treatment course may be necessary after exposure to anti-TNF-alpha.
El ensayo de liberación de interferón gamma (IGRA) se utiliza para detectar tuberculosis latente antes de los tratamientos biológicos en el contexto de sospecha de reumatismo inflamatorio.
Presentamos el caso de una mujer de 50 años con IGRA negativo antes de la introducción de adalimumab por presunta espondiloartritis axial.
El empeoramiento de los síntomas bajo tratamiento llevó a nuevas investigaciones y posteriormente se estableció el diagnóstico de tuberculosis (TB) diseminada con localizaciones pulmonar y óseas múltiples como espondilitis y sacroilitis. La historia de la paciente reveló una exposición pasada a la TB. Esta observación ilustra las limitaciones del IGRA en tal situación debido a su rendimiento variable para el diagnóstico de la TB activa.
El diagnóstico erróneo es frecuente en la TB ósea debido a signos inespecíficos. Llamamos la atención sobre la importancia de una evaluación de riesgo global antes de la introducción de un tratamiento biológico para la sospecha de reumatismo inflamatorio crónico, y recordamos los factores de riesgo para falsos negativos del IGRA. Puede ser necesario un curso de tratamiento prolongado después de la exposición al tratamiento anti-TNF-alfa.
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