Subject(s)
Influenza A Virus, H1N1 Subtype , Influenza, Human/complications , Influenza, Human/virology , Leukoencephalitis, Acute Hemorrhagic/diagnosis , Leukoencephalitis, Acute Hemorrhagic/virology , Antiviral Agents/therapeutic use , Child, Preschool , Diagnosis, Differential , Drug Therapy, Combination , Female , Humans , Immunoglobulin G/therapeutic use , Influenza, Human/drug therapy , Leukoencephalitis, Acute Hemorrhagic/drug therapy , Neuroimaging/methods , Zanamivir/therapeutic useABSTRACT
Data are lacking on the performance of interferon-gamma release assays (IGRAs) in children. Although IGRAs are recommended for screening for latent tuberculosis infection (LTBI), many clinicians wish to employ them as a diagnostic test for active tuberculosis (TB). The objective of the present study was to compare the performance of the two commercially available IGRAs and the tuberculin skin test (TST) side-by-side in children with active TB and LTBI. In a prospective study, 209 children were investigated for active (n = 91) or latent TB (n = 118). TST, QuantiFERON-TB Gold In-tube (QFG-IT; Cellestis, Carnegie, Australia) and T-SPOT.TB (Oxford Immunotec, Abingdon, UK) assays were simultaneously used. For culture-confirmed active TB, the sensitivity of the TST was 83%, compared with 80% for QFG-IT and 58% for T-SPOT.TB. IGRAs did not perform significantly better than TST, although QFG-IT was significantly better than T-SPOT.TB. The agreement between QFG-IT and T-SPOT.TB in culture-confirmed TB was poor at 66.7%. In LTBI, the agreement between QFG-IT and T-SPOT.TB was very good (92%) with moderate agreement between TST and T-SPOT.TB (75%) and QFG-IT and TST (77%). A negative interferon-gamma release assay should not dissuade paediatricians from diagnosing and treating presumed active tuberculosis. If used for diagnosis of latent tuberculosis infection, interferon-gamma release assays could significantly reduce the numbers of children receiving chemoprophylaxis. Very good concordance between both tests was found.
Subject(s)
Immunologic Tests/methods , Interferon-gamma/blood , Tuberculosis, Pulmonary/diagnosis , Adolescent , Child, Preschool , Female , Humans , Infant , Male , Mycobacterium tuberculosis , Prospective Studies , Sensitivity and Specificity , Time Factors , Tuberculin Test , Tuberculosis, Pulmonary/immunologyABSTRACT
Immunization with radiation-attenuated Plasmodium spp. sporozoites induces sterile protective immunity against parasite challenge. This immunity is targeted primarily against the intrahepatic parasite and appears to be sustained long term even in the absence of sporozoite exposure. It is mediated by multifactorial mechanisms, including T cells directed against parasite antigens expressed in the liver stage of the parasite life cycle and antibodies directed against sporozoite surface proteins. In rodent models, CD8+ T cells have been implicated as the principal effector cells, and IFN-gamma as a critical effector molecule. IL-4 secreting CD4+ T cells are required for induction of the CD8+ T cell responses, and Th1 CD4+ T cells provide help for optimal CD8+ T cell effector activity. Components of the innate immune system, including gamma-delta T cells, natural killer cells and natural killer T cells, also play a role. The precise nature of pre-erythrocytic stage immunity in humans, including the contribution of these immune responses to the age-dependent immunity naturally acquired by residents of malaria endemic areas, is still poorly defined. The importance of immune effector targets at the pre-erythrocytic stage of the parasite life cycle is highlighted by the fact that infection-blocking immunity in humans rarely, if ever, occurs under natural conditions. Herein, we review our current understanding of the molecular and cellular aspects of pre-erythrocytic stage immunity.
