There are a number of ELISA Kits available for the measurement of IL-18, another term for the human protein, interleukin 18. Other synonyms may include: IFN-gamma-inducing factor, IL-1 gamma, iboctadekin, interleukin 18 (interferon-gamma-inducing factor), IGIF, IL-18, and IL-1g. It is encoded by the IL18 gene to yield a protein 193 amino acids in length and 22.3 kDa in size. However, there are up to 2 reported isoforms. The protein is categorized into the IL-1 family.