IL6 and tuberculosis: Patients with microbiologically verified disease were used as positive controls and healthy subjects with no exposure or risk factor for TB were used as negative controls to determine a cut-off level for several cytokines and chemokines: IFN-γ, IL-2, tumor necrosis factor alpha (TNF-α), IP-10, IL-12, IL-6, IL-4, IL-5, IL-13, IL-17, macrophage inflammatory protein 1 beta (MIP-1β), granulocyte macrophage-colony stimulating factor (GM-CSF), interferon-alfa 2 (IFN-α2) and IL-10.