A comparative analysis of the antigenic, structural, and functional properties of three different preparations of recombinant human interleukin-18.
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.
Kikkawa
S
S
Department of Immunology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Japan.
Shida
K
K
Okamura
H
H
Begum
N A
NA
Matsumoto
M
M
Tsuji
S
S
Nomura
M
M
Suzuki
Y
Y
Toyoshima
K
K
Seya
T
T
D000818:Animals; D000911:Antibodies, Monoclonal; D000941:Antigens / Q000737:chemistry*; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000737:chemistry; D006801:Humans; D066298:In Vitro Techniques; D007369:Interferon Inducers / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000494:pharmacology; D020382:Interleukin-18 / Q000737:chemistry* / Q000276:immunology* / Q000494:pharmacology; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology; D008214:Lymphocytes / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000276:immunology / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D000941:Antigens; D000939:Epitopes; D007369:Interferon Inducers; D020382:Interleukin-18; D011994:Recombinant Proteins; D018664:Interleukin-12; D007371:Interferon-gamma