WordNet (r) 3.0 (2006):

tumour necrosis factor
    n 1: a proinflammatory cytokine that is produced by white blood
         cells (monocytes and macrophages); has an antineoplastic
         effect but causes inflammation (as in rheumatoid arthritis)
         [syn: tumor necrosis factor, tumour necrosis factor,
         TNF]