Novel IL-12 family members shed light on the orchestration of Th1 responses

Trends Immunol. 2003 Apr;24(4):207-12. doi: 10.1016/s1471-4906(03)00067-x.


Interleukin-12 (IL-12), which is composed of a p35 and a p40 subunit, is a proinflammatory natural-killer (NK) cell-stimulating, Th1-inducing and Th1-maintaining cytokine, which promotes cell-mediated immunity. On activation, heterodimeric IL-12 is found in small amounts, whereas free p40 is produced in excess. Besides IL-12, other p40-dependent molecules exist that orchestrate Th1 responses. Homodimeric p40 can act as an IL-12 antagonist by competing for its receptor. Recent data also reveal potential immunostimulatory functions of p40. In addition, p40 can be covalently linked to a p35-related protein p19. This heterodimer is known as IL-23 and has activities on memory T cells. Finally, IL-27, the latest addition to this family, is a heterodimer composed of the p40-related protein EBI3 (Epstein-Barr virus-induced gene 3) and the p35-related protein p28. IL-27 is involved in early Th1 initiation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Communicable Diseases / immunology
  • Humans
  • Immunologic Memory
  • Interleukin-12 / immunology
  • Interleukin-12 / metabolism*
  • Interleukin-23
  • Interleukin-23 Subunit p19
  • Interleukins / metabolism
  • Th1 Cells / immunology*


  • IL23A protein, human
  • Interleukin-23
  • Interleukin-23 Subunit p19
  • Interleukins
  • MYDGF protein, human
  • Interleukin-12