Interleukin 12 (IL-12) is a disulphide-bonded heterodimer consisting of a 35kDa alpha subunit (e.g. Swiss:P29459) and a 40kDa beta subunit (e.g. Swiss:P29460). It is involved in the stimulation and maintenance of Th1 cellular immune responses, including the normal host defence against various intracellular pathogens, such as Leishmania, Toxoplasma, measles virus and HIV. IL-12 also has an important role in pathological Th1 responses, such as in inflammatory bowel disease and multiple sclerosis. Suppression of IL-12 activity in such diseases may have therapeutic benefit. On the other hand, administration of recombinant IL-12 may have therapeutic benefit in conditions associated with pathological Th2 responses [1,2].

1: Il-12: keeping cell-mediated immunity alive frontlines - topic review. Park AY, Scott P; Scand J Immunol 2001;53:529-532. PMID:11422900

2: The interleukin-12/interleukin-12-receptor system: role in normal and pathologic immune responses. Gately MK, Renzetti LM, Magram J, Stern AS, Adorini L, Gubler U, Presky DH; Annu Rev Immunol 1998;16:495-521. PMID:9597139