Interleukin-12 subunit beta (IL-12B) (IL-12B)

Interleukin-12 subunit beta (IL-12B), commonly known as p40, is a shared subunit of the heterodimeric cytokines Interleukin-12 (IL-12) and Interleukin-23 (IL-23) (UniProt: P29460). IL-12 (p35/p40) is a primary driver of Type 1 T helper (Th1) cell differentiation and interferon-gamma production, while IL-23 (p19/p40) is essential for the survival and expansion of Th17 cells, which produce IL-17 and IL-22 (PubMed: 15771580). Dysregulation of the IL-12/IL-23 axis is a hallmark of several chronic inflammatory diseases, including psoriasis, Crohn's disease, and ulcerative colitis (StatPearls: NBK537220). Therapeutic monoclonal antibodies, such as ustekinumab, target the p40 subunit to simultaneously inhibit both IL-12 and IL-23 signaling by preventing their binding to the IL-12 receptor beta 1 (IL-12Rβ1) subunit (DrugBank: DB05609). This dual inhibition provides a broad anti-inflammatory effect but also necessitates monitoring for increased susceptibility to infections, particularly mycobacterial and fungal pathogens (FDA Label: Stelara). By blocking the p40 subunit, these therapies effectively interrupt the pathogenic T-cell pathways that drive tissue damage in autoimmune conditions.

Other names

IL-12p40Interleukin-12 subunit p40Interleukin-23 subunit p40Natural killer cell stimulatory factor 2NKSF2Cytokine CLMF p40Cytotoxic lymphocyte maturation factor 2CLMF2Interleukin-23 via p40 subunit

Monoclonal antibodies bind with high affinity to the p40 subunit of the IL-12 and IL-23 cytokines, preventing them from binding to the IL-12Rβ1 receptor on the surface of T cells and natural killer cells, thereby blocking downstream JAK-STAT signaling (specifically STAT4 for IL-12 and STAT3 for IL-23) and inhibiting the inflammatory response (PubMed: 18046404).