IL4 and infection: Th1 secrete interleukin-2 (IL-2), TNF-alpha and interferon-gamma (IFN-γ) and this response is associated with controlling infection while Th2 cells secrete interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-10 (IL-10), and transformation growth factor beta (TGF-β) and correlate with disease progression [7, 8].