New data from University of London, Imperial College illuminate research in HIV/AIDS co-infection
2008 JAN 21 -- "There are limited data on the efficacy of T cell-based assays to detect tuberculosis (TB) antigen-specific responses in immune-deficient human immunodeficiency virus (HIV) patients. The aim of this study is to determine whether TB antigen-specific immune responses can be detected in patients with HIV-1 infection, especially in those with advanced disease (CD4 T cell count < 300 cells/mu l)," investigators in London, the United Kingdom report. "An enzyme-linked immunospot (ELISPOT) assay, which detects interferon (IFN)-gamma secreted by T cells exposed to TB antigens, was used to assess specific immune responses in a prospective study of 201 HIV-1-infected patients with risk factors for TB infection, attending a single HIV unit. The performance of the ELISPOT assay to detect TB antigen-specific immune responses is independent of CD4 T cell counts in HIV-1 patients. The sensitivity and specificity of this assay for the diagnosis of active tuberculosis does not differ significantly from values obtained in immunocompetent subjects. The negative predictive value of the TB ELISPOT test is 98.2%. A positive predictive value of 86% for the diagnosis of active tuberculosis was found when the combined number of early secretory antigen target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) IFN-gamma spots to CD4 T cell count ratio was > 1.5. TB antigen-specific immune responses can be detected in HIV patients with low CD4 T cell counts using ELISPOT technology in a routine diagnostic laboratory and is a useful test to exclude TB infection in immune-deficient HIV-1 patients," wrote S.A. Clark and colleagues, University of London, Imperial College. The researchers concluded: "A combination of TB antigen-specific IFN-gamma responses and CD4 T cell counts has the potential to distinguish active tuberculosis from latent infection." Clark and colleagues published their study in Clinical and Experimental Immunology (Tuberculosis antigen-specific immune responses can be detected using enzyme-linked immunospot technology in human immunodeficiency virus (HIV)-1 patients with advanced disease. Clinical and Experimental Immunology, 2007;150(2):238-244). For additional information, contact P. Kelleher, University of London Imperial College, Chelsea & Westminster Hospital, Dept. of Immunology, London, UK. The publisher of the journal Clinical and Experimental Immunology can be contacted at: Blackwell Publishing, 9600 Garsington Rd., Oxford OX4 2DQ, Oxon, England. Keywords: United Kingdom, London, HIV/AIDS Co-Infection, AIDS, Acquired Immune Deficiency Syndrome, Acquired Immunodeficiency Syndrome, Cutaneous Tuberculosis, HIV, Human Immunodeficiency Virus Bacterial Infection, Immunology, Infectious Disease, Interferon, Interferon Gamma, Mycobacteria, Mycobacterium Tuberculosis, Sexually Transmitted Disease, Viral, Virology, University of London, Imperial College. This article was prepared by Tuberculosis Week editors from staff and other reports. Copyright 2008, Tuberculosis Week via NewsRx.com.
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