IL-1 is a name that designates two pleiotropic cytokines, IL-1 alpha (IL-1F1) and IL-1 beta (IL-1F2), which are the products of distinct genes. IL-1 alpha and IL-1 beta are structurally related polypeptides that share approximately 27% amino acid (aa) identity in porcine. Both proteins are produced by a wide variety of cells in response to inflammatory agents, infections, or microbial endotoxins. While IL-1 alpha and IL-1 beta are regulated independently, they bind to the same receptor and exert identical biological effects. IL-1 RI binds directly to IL-1 alpha or IL-1 beta and then associates with IL-1 R accessory protein (IL-1 R3/IL-1 R AcP) to form a high-affinity receptor complex that is competent for signal transduction. IL-1 RII has high affinity for IL-1 beta but functions as a decoy receptor and negative regulator of IL-1 beta activity. IL-1ra functions as a competitive antagonist by preventing IL-1 alpha and IL-1 beta from interacting with IL-1 RI. The porcine IL-1 beta cDNA encodes a 267 aa precursor. A 114 aa propeptide is cleaved intracellularly by the cysteine protease IL-1 beta -converting enzyme (Caspase-1/ICE) to generate the active cytokine. The 17 kDa mature porcine IL-1 beta shares 63%-70% aa sequence identity with canine, cotton rat, equine, feline, human, mouse, rat, and rhesus IL-1 beta.

Interleukin-1 alpha (IL1a) is also known as IL-1A, IL1,and is a cytokine of the interleukin-1 family. Among various species, the amino acid sequence of mature IL-1 alpha is conserved 60% to 70% and human IL-1 has been found to be biologically active on murine cell lines. It possesses metabolic, physiological, haematopoietic activities, and plays one of the central roles in the regulation of the immune responses. IL-1 is a major immunoregulatory/proinflammatory cytokine which also affects fibroblast proliferation and function and therefore it was of interest to investigate whether its constitutive expression influences the in vivo tumorigenic potential of transformed fibroblastoid cell lines