Publications (2)2.37 Total impact
[show abstract] [hide abstract]
ABSTRACT: The interferon-gamma (IFN-γ) release assay (IGRA) is an in vitro extension of the century-old in vivo tuberculin skin test, better known as the TST. Shortcomings to the TST are multifactorial and include limitations in sensitivity and specificity. IGRAs improve diagnostic specificity by using antigens not found in the Bacille Calmette-Guérin, a vaccine given in most countries. IGRAs capture the IFN-γ produced by T cells in response to antigen stimulation. The ELISPOT immediately captures IFN-γ produced directly from each cell, resulting in the generation of a cellular "footprint." The dimensions and intensity of the generated footprint indicate the avidity of the secreting cell. We show a further improvement in IGRAs by addition of interleukin-7 (IL-7). IL-7 reduces T-cell apoptosis and stabilizes IFN-γ message. In addition to increasing the number of spots in the ELISPOT T-SPOT.TB platform, IL-7 increased IFN-γ production per cell as measured by an increase in spot size with no change in spot distribution.Methods in molecular biology (Clifton, N.J.) 01/2012; 792:229-41.
Article: Enhancement of human antigen-specific memory T-cell responses by interleukin-7 may improve accuracy in diagnosing tuberculosis.[show abstract] [hide abstract]
ABSTRACT: Children and immunocompromised adults are at an increased risk of tuberculosis (TB), but diagnosis is more challenging. Recently developed gamma interferon (IFN-gamma) release assays provide increased sensitivity and specificity for diagnosis of latent TB, but their use is not FDA approved in immunocompromised or pediatric populations. Both populations have reduced numbers of T cells, which are major producers of IFN-gamma. Interleukin 7 (IL-7), a survival cytokine, stabilizes IFN-gamma message and increases protein production. IL-7 was added to antigen-stimulated lymphocytes to improve IFN-gamma responses as measured by enzyme-linked immunosorbent assay (ELISA) and enzyme-linked immunospot (ELISPOT) assay. Antigens used were tetanus toxoid (n = 10), p24 (from human immunodeficiency virus [HIV], n = 9), and TB peptides (n = 15). Keyhole limpet hemocyanin was used as a negative control, and phytohemagglutinin was the positive control. IL-7 improved antigen-specific responses to all antigens tested including tetanus toxoid, HIV type 1 p24, and TB peptides (ESAT-6 and CFP-10) with up to a 14-fold increase (mean = 3.8), as measured by ELISA. Increased IFN-gamma responses from controls, HIV-positive patients, and TB patients were statistically significant, with P values of <0.05, 0.01, and 0.05, respectively. ELISPOT assay results confirmed ELISA findings (P values of <0.01, 0.02, and 0.03, respectively), with a strong correlation between the two tests (R(2) = 0.82 to 0.99). Based on average background levels, IL-7 increased detection of IFN-gamma by 39% compared to the level with antigen alone. Increased production of IFN-gamma induced by IL-7 improves sensitivity of ELISA and ELISPOT assays for all antigens tested. Further enhancement of IFN-gamma-based assays might improve TB diagnosis in those populations at highest risk for TB.Clinical and vaccine immunology: CVI 09/2008; 15(10):1616-22. · 2.37 Impact Factor