This gene encodes the beta subunit p40 of the Interleukin 12 (IL-12) family of cytokines. Members of the IL-12 family form heterodimers consisting of heavy and light subunits linked by disulfide bonds. The product of this gene, p40, is a subunit of interleukins IL-12 and IL-23. [provided by RefSeq, Dec 2014]

IL12B: Cytokine that 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. Defects in IL12B are a cause of mendelian susceptibility to mycobacterial disease (MSMD); also known as familial disseminated atypical mycobacterial infection. This rare condition confers predisposition to illness caused by moderately virulent mycobacterial species, such as Bacillus Calmette-Guerin (BCG) vaccine and environmental non-tuberculous mycobacteria, and by the more virulent Mycobacterium tuberculosis. Other microorganisms rarely cause severe clinical disease in individuals with susceptibility to mycobacterial infections, with the exception of Salmonella which infects less than 50% of these individuals. The pathogenic mechanism underlying MSMD is the impairment of interferon-gamma mediated immunity, whose severity determines the clinical outcome. Some patients die of overwhelming mycobacterial disease with lepromatous-like lesions in early childhood, whereas others develop, later in life, disseminated but curable infections with tuberculoid granulomas. MSMD is a genetically heterogeneous disease with autosomal recessive, autosomal dominant or X-linked inheritance. Genetic variations in IL12B are a cause of susceptibility to psoriasis type 11 (PSORS11). Psoriasis is a common, chronic inflammatory disease of the skin with multifactorial etiology. It is characterized by red, scaly plaques usually found on the scalp, elbows and knees. These lesions are caused by abnormal keratinocyte proliferation and infiltration of inflammatory cells into the dermis and epidermis. Belongs to the type I cytokine receptor family. Type 3 subfamily.

Protein type: Secreted, signal peptide; Cytokine; Secreted

Cellular Component: extracellular space; membrane; interleukin-12 complex; cytoplasm; extracellular region

Molecular Function: identical protein binding; hematopoietin/interferon-class (D200-domain) cytokine receptor activity; protein binding; interleukin-12 alpha subunit binding; protein homodimerization activity; growth factor activity; hematopoietin/interferon-class (D200-domain) cytokine receptor binding; protein heterodimerization activity; interleukin-23 receptor binding; cytokine activity

Biological Process: positive regulation of granulocyte macrophage colony-stimulating factor production; positive regulation of cell adhesion; negative regulation of interleukin-10 production; positive regulation of T-helper 1 type immune response; positive regulation of osteoclast differentiation; positive regulation of interleukin-12 production; positive regulation of T cell mediated cytotoxicity; negative regulation of smooth muscle cell proliferation; positive regulation of NK T cell proliferation; natural killer cell activation; positive regulation of tyrosine phosphorylation of Stat4 protein; defense response to Gram-negative bacterium; sensory perception of pain; positive regulation of activated T cell proliferation; positive regulation of natural killer cell activation; positive regulation of interleukin-10 production; positive regulation of tyrosine phosphorylation of Stat3 protein; cell surface receptor linked signal transduction; positive regulation of lymphocyte proliferation; natural killer cell activation during immune response; negative regulation of inflammatory response to antigenic stimulus; positive regulation of T cell proliferation; cell cycle arrest; defense response to virus; positive regulation of interleukin-17 production; cell migration; positive regulation of natural killer cell proliferation; positive regulation of NK T cell activation; T-helper cell differentiation; positive regulation of natural killer cell mediated cytotoxicity directed against tumor cell target; positive regulation of tumor necrosis factor production; defense response to protozoan; regulation of tyrosine phosphorylation of Stat1 protein; response to UV-B; positive regulation of interferon-gamma production; negative regulation of interleukin-17 production; positive regulation of tyrosine phosphorylation of Stat5 protein; positive regulation of mononuclear cell proliferation; positive regulation of defense response to virus by host