[2] Despite sharing many structural features and molecular partners, they mediate surprisingly diverse functional effects.

Enhanced functional response is demonstrated by IFN-γ production and killing of target cells.

Because of its ability to induce immune responses and its anti-angiogenic activity, there has been an interest in testing IL-12 as a possible anti-cancer drug.

[7] An extensive review and visualization of IL-12 signaling can be found at the peer-reviewed pathway database Reactome: Interleukin-12 family IL-12 is linked with autoimmunity.

[10] It promotes the development of Th1 responses and is a powerful inducer of IFNγ production by T and NK cells.

[11] A child with Bacillus Calmette–Guérin and Salmonella enteritidis infection was found to have a large homozygous deletion within the IL-12 p40 subunit gene, precluding expression of functional IL-12 p70 cytokine by activated dendritic cells and phagocytes.

T and NK cells from seven unrelated patients who had severe idiopathic mycobacterial and Salmonella infections failed to produce IFNγ when stimulated with IL-12.

Defective Th1 and Th17 immune responses leading to chronic mucocutaneous candidiasis result from a mutation further downstream in the IL-12 signalling pathway.

The trait was mapped to mutations in the STAT1 gene, which were associated with lower production of interferon-γ, IL-17, and IL-22 in response to IL-12 or IL-23 receptor associated Jak2 and Tyk2 activity.