A comparative analysis of the antigenic, structural, and functional properties of three different preparations of recombinant human interleukin-18

J Interferon Cytokine Res. 2000 Feb;20(2):179-85. doi: 10.1089/107999000312586.


We compared the structural and functional properties of three recombinant human interleukin-18 (rIL-18) preparations, commercially available (Pep rIL-18) and prepared in our laboratory (active and inactive, according to their ability to potentiate IL-12-mediated interferon-gamma [IFN-gamma] induction in lymphocytes). All three preparations showed multimer formation on SDS-PAGE/immunoblotting using monoclonal antibodies (mAb) against the inactive form of rIL-18. In contrast, only the 18-kDa bands were recognized in each sample by mAb against the active form of rIL-18. The amounts of multimers and the 18-kDa moiety of Pep rIL-18 resembled those of the inactive rather than the active form. Likewise, the reaction profile of Pep rIL-18 toward mAb was very similar to that of inactive but not active rIL-18 on sandwich ELISA. Pep rIL-18 potentiated IFN-gamma-inducing activity together with IL-12, but its potency was 100-fold less than that of the active rIL-18, and excess doses were required for its activity. The inactive rIL-18 showed virtually no IFN-gamma-inducing ability, but when reduced and reconstituted, it inhibited the IFN-gamma-inducing activity of active rIL-18. These results suggest that there are two categories of recombinant IL-18 that are structurally, functionally, and antigenically different, and the mAb 125-2H and 21 can discriminate these two IL-18 populations by recognizing the epitopes specifically expressed on active and inactive IL-18, respectively.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Antigens / chemistry*
  • CD4-Positive T-Lymphocytes / drug effects
  • CD4-Positive T-Lymphocytes / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Epitopes / chemistry
  • Humans
  • In Vitro Techniques
  • Interferon Inducers / chemistry
  • Interferon Inducers / immunology
  • Interferon Inducers / pharmacology
  • Interferon-gamma / biosynthesis
  • Interleukin-12 / pharmacology
  • Interleukin-18 / chemistry*
  • Interleukin-18 / immunology*
  • Interleukin-18 / pharmacology
  • Killer Cells, Natural / drug effects
  • Killer Cells, Natural / immunology
  • Lymphocytes / drug effects*
  • Lymphocytes / immunology*
  • Mice
  • Molecular Weight
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / immunology
  • Recombinant Proteins / pharmacology


  • Antibodies, Monoclonal
  • Antigens
  • Epitopes
  • Interferon Inducers
  • Interleukin-18
  • Recombinant Proteins
  • Interleukin-12
  • Interferon-gamma