Furthermore, peripheral blood mononuclear cells (PBMC) from a subset of four patients (three TB-IRIS and one non-IRIS) were stimulated with PPD antigen and those with TB-IRIS secreted significantly higher concentrations of Th1 (IL-2, IL-12, IFN-γ, and IP-10) and other (TNF-α, IL-1β, IL-6, IL-10, RANTES, and MCP-1) cytokines and chemokines, while Th2 cytokines (IL-4, IL-5, IL-13, and IL15) were not detected [44]. This evidence concerns the gene IL6 and tuberculosis.