ESTABLISHMENT OF THE CELLS USEFUL FOR MURINE INTERLEUKIN-18 BIOASSAY BY INTRODUCING MURINE INTERLEUKIN-18 RECEPTOR CDNA INTO HUMAN MYELOMONOCYTIC KG-1 CELLS

We genetically engineered human myelomonocytic KG-1 cells by introduci ng cDNA of murine interleukin-18 receptor (MuIL-18R) and established h uman cells which were capable of responding to MuIL-18. These cells ex pressed larger number of MuIL-18R(> 13,000 sites/cell) than intrinsic human IL-18 receptor (HuIL-18R) (< 2,500 sites/cell). And the cells re sponded to MuIL-18 as well as to HuIL-18 in a dose-dependent manner, a nd produced large amounts of interferon-gamma (IFN-gamma). We could es timate the amount of murine IL-18 based on the amounts of IFN-gamma pr oduced by these cells. The stoichiometry was observed up to 150 ng/ml of MuIL-18. By using these cells, a large amount of MuIL-18 (448 +/- 8 9.2 ng/ml) was detected in sera of Propionibacterium acnes (P. acnes)/ lipopolysaccharide (LPS)-treated endotoxic mice (the same conditions i n which IL-18 was first identified). These cells provide us with a use ful tool for determining the bioactivity of MuIL-18. (C) 1998 Elsevier Science B.V. All rights reserved.