Interleukin-12 subunit beta (p40) (IL-12B)

Interleukin-12 subunit beta, commonly known as p40, is a critical cytokine component that serves as a shared subunit for both Interleukin-12 (IL-12) and Interleukin-23 (IL-23) [UniProt, 2024]. When paired with the p35 subunit, it forms IL-12, which drives Type 1 T helper (Th1) cell differentiation; when paired with the p19 subunit, it forms IL-23, which is essential for the maintenance and expansion of Th17 cells [Nature, 2003]. This dual role makes the p40 subunit a central regulator of the inflammatory response, particularly in the IL-23/IL-17 signaling axis. Dysregulation and overproduction of p40-containing cytokines are strongly associated with the pathogenesis of chronic inflammatory conditions such as psoriasis, Crohn's disease, and ulcerative colitis [PubMed, 2021]. Therapeutic strategies targeting the p40 subunit, such as the monoclonal antibody ustekinumab, effectively neutralize both IL-12 and IL-23 signaling by preventing their binding to the IL-12 receptor beta 1 (IL-12Rβ1) chain [DrugBank, 2024]. This inhibition leads to a reduction in the production of downstream pro-inflammatory cytokines like interferon-gamma and IL-17, providing significant clinical benefit in autoimmune diseases [StatPearls, 2023].

Other names

IL-12Bp40Cytotoxic lymphocyte maturation factor 2CLMF2Natural killer cell stimulatory factor 2NKSF2

Binds to the p40 subunit shared by the IL-12 and IL-23 cytokines, thereby preventing these cytokines from binding to their shared receptor, IL-12Rβ1, and inhibiting downstream signaling pathways such as JAK-STAT [DrugBank, 2024; StatPearls, 2023].