Interleukin 12 (IL12) can act as a growth factor for activated T and NK cells, enhance the lytic activity of NK/lymphokine activated killer cells, and stimulate the production of IFN gamma by resting PBMC. IL12 induces IFN gamma, TNF alpha production in T and NK cells, costimulation of PBL proliferation, proliferation/differentiation of TH1 T lymphocytes. It is downregulated by IL10, homodimeric p40 antagonistic to functional p70 heterodimer. IL12R beta 1 binds p40 but when dimeric with IL12R beta 2 binds p35.Synonyms: CLMF p40, Cytotoxic lymphocyte maturation factor 40 kDa subunit, IL-12 subunit p40, IL-12B, Interleukin-12B, NK cell stimulatory factor chain 2, NKSF2