TNF and infection: Previous studies have demonstrated the production of interferon-gamma (IFN-γ), interleukin 12 (IL-12), nitric oxide (NO) and tumour necrosis factor alpha (TNF-α) in early stages of infection and later interleukin 13 (IL-13), interleukin 4 (IL-4) and interleukin 10 (IL-10) [15, 17, 18].