Evaluation of a lateral-flow nanoparticle fluorescence assay for TB infection diagnosis

BACKGROUND:

Programmatic management of TB infection is a critical component of the WHO End TB Strategy. Interferon-gamma release assays (IGRAs) overcome some limitations of the tuberculin skin test, but implementation of IGRA testing in low-resource settings is challenging.

METHODS:

In this feasibility study, we evaluated performance of a novel digital lateral-flow assay, the QIAreach® QuantiFERON® TB (QIAreach-QFT) test, against the QuantiFERON®-TB Gold Plus (QFT-Plus) assay. A population with a mix of risk factors for TB infection (111 donors) were sampled over multiple days. A total of 207 individual blood samples were tested according to the manufacturer’s instructions.

RESULTS:

The overall percentage agreement was 95.6% (two-sided 95% CI 91.8–98), with a positive percentage agreement (i.e., sensitivity) of 100% (95% CI 94.7–100) and a negative percentage agreement (i.e., specificity) of 95.6% (95% CI 90.6–98.4). All QFT-Plus positive specimens with TB1-Nil and TB2-Nil values less than 1 IU/ml tested positive on QIAreach-QFT.

CONCLUSIONS:

QIAreach QFT is a deployable, accurate testing solution for decentralised testing. It has the potential to overcome key hurdles for TB infection screening in high-burden settings thus helping to achieve the WHO End TB programme goals.

The role of endothelial dysfunction in the pathogenesis of impaired diabetic wound healing: a novel therapeutic target?

The global burden of diabetes is attributed to its multiple associated complications including impaired wound healing which can ultimately result in amputation. Peripheral vascular disease, infection, neuropathy and abnormal local cellular and cytokine activity are some of the traditionally cited pathological instigators of defective diabetic wound repair. Despite intensive research and subsequent advances in diabetic wound care technology a single treatment with measurable clinical impact has yet to be determined. The phenomenon of endothelial dysfunction as seen in atherosclerosis and recently identified as a characteristic of diabetic vasculature may contribute to impaired cutaneous healing in this group. Indicators of endothelial dysfunction have been demonstrated in diabetic wounds by a number of investigators. Successful results are being obtained with modifiers of endothelial function in the management of cardiovascular disease. We hypothesise that endothelial dysfunction plays a substantial contributory role in the pathogenesis of wound healing impairment of diabetes and holds potential as a target for therapeutic intervention.

Mechanisms of drug-induced lupus. II. T cells overexpressing lymphocyte function-associated antigen 1 become autoreactive and cause a lupuslike disease in syngeneic mice

Current theories propose that systemic lupus erythematosus develops when genetically predisposed individuals are exposed to certain environmental agents, although how these agents trigger lupus is uncertain. Some of these agents, such as procainamide, hydralazine, and UV-light inhibit T cell DNA methylation, increase lymphocyte function-associated antigen 1 (LFA-1) (CD11a/CD18) expression, and induce autoreactivity in vitro, and adoptive transfer of T cells that are made autoreactive by this mechanism causes a lupuslike disease. The mechanism by which these cells cause autoimmunity is unknown. In this report, we present evidence that LFA-1 overexpression is sufficient to induce autoimmunity. LFA-1 overexpression was induced on cloned murine Th2 cells by transfection, resulting in autoreactivity. Adoptive transfer of the transfected, autoreactive cells into syngeneic recipients caused a lupuslike disease with anti-DNA antibodies, an immune complex glomerulonephritis and pulmonary alveolitis, similar to that caused by cells treated with procainamide. These results indicate that agents or events which modify T cell DNA methylation may induce autoimmunity by causing T cell LFA-1 overexpression. Since T cells from patients with active lupus have hypomethylated DNA and overexpressed LFA-1, this mechanism could be important in the development of human autoimmunity.

The role of protein kinase C in transmembrane signaling by the T cell antigen receptor complex. Effects of stimulation with soluble or immobilized CD3 antibodies

Phorbol esters, such as phorbol myristate acetate (PMA), are known to be potent co-stimulants with calcium ionophores for activation of T lymphocytes. The most extensively studied intracellular effect of PMA is its ability to activate the cytoplasmic enzyme protein kinase C (pkC). Herein, we examined the role of pkC activation during T cell activation. During physiologic activation, this enzyme is activated by diacylglycerol which is generated through the hydrolysis of polyphosphoinositides. Therefore, we studied the activation of T lymphocytes induced by a synthetic diacylglycerol, dioctanoylglycerol. In contrast to PMA, this compound can be metabolized in T cells and presumably more closely mimics physiologic activation of pkC. Dioctanoylglycerol together with reagents that induce increases in intracellular free Ca2+ concentration, Ca2+ ionophores, or anti-cluster designation (CD)3 monoclonal antibodies (mAb) were able to induce interleukin 2 receptor expression and proliferation of T lymphocytes. Previous studies have demonstrated that the stimulation of T cells via the CD3/T cell antigen receptor complex by mAb against CD3 leads to an increase in cytoplasmic free Ca2+ and to an activation of pkC. Paradoxically, however, soluble CD3 antibodies do not cause proliferation of resting purified T cells. Inasmuch as immobilization of CD3 mAb has been shown to influence the agonist properties of such antibodies, we compared the ability of soluble and immobilized CD3 mAb to activate pkC. We demonstrated herein that soluble CD3 mAb cause only a very transient activation of pkC in the T cell leukemic line Jurkat. This pkC activation is markedly prolonged when Jurkat cells are stimulated with immobilized rather than soluble CD3 antibodies. These studies suggest that activation of pkC plays a major role in T cell activation and that the activation of pkC is influenced by the form in which CD3 mAb is presented to T cells.

The role of protein kinase C in transmembrane signaling by the T cell antigen receptor complex. Effects of stimulation with soluble or immobilized CD3 antibodies

Phorbol esters, such as phorbol myristate acetate (PMA), are known to be potent co-stimulants with calcium ionophores for activation of T lymphocytes. The most extensively studied intracellular effect of PMA is its ability to activate the cytoplasmic enzyme protein kinase C (pkC). Herein, we examined the role of pkC activation during T cell activation. During physiologic activation, this enzyme is activated by diacylglycerol which is generated through the hydrolysis of polyphosphoinositides. Therefore, we studied the activation of T lymphocytes induced by a synthetic diacylglycerol, dioctanoylglycerol. In contrast to PMA, this compound can be metabolized in T cells and presumably more closely mimics physiologic activation of pkC. Dioctanoylglycerol together with reagents that induce increases in intracellular free Ca2+ concentration, Ca2+ ionophores, or anti-cluster designation (CD)3 monoclonal antibodies (mAb) were able to induce interleukin 2 receptor expression and proliferation of T lymphocytes. Previous studies have demonstrated that the stimulation of T cells via the CD3/T cell antigen receptor complex by mAb against CD3 leads to an increase in cytoplasmic free Ca2+ and to an activation of pkC. Paradoxically, however, soluble CD3 antibodies do not cause proliferation of resting purified T cells. Inasmuch as immobilization of CD3 mAb has been shown to influence the agonist properties of such antibodies, we compared the ability of soluble and immobilized CD3 mAb to activate pkC. We demonstrated herein that soluble CD3 mAb cause only a very transient activation of pkC in the T cell leukemic line Jurkat. This pkC activation is markedly prolonged when Jurkat cells are stimulated with immobilized rather than soluble CD3 antibodies. These studies suggest that activation of pkC plays a major role in T cell activation and that the activation of pkC is influenced by the form in which CD3 mAb is presented to T cells.

Wegener's granulomatosis: isolated involvement of the trachea and larynx

A 26 year old man with subacute hoarseness and stridor was shown to have Wegener's granulomatosis isolated to the trachea and larynx. Although isolated laryngeal Wegener's is unusual, a review of the literature suggests that early treatment with cyclophosphamide is warranted.