Quantitative in vitro bioassay for recombinant human interleukin-11

A cell culture-based in vitro bioassay was developed to measure the biological activity of recombinant human interleukin-11 (rhIL-11). The bioassay measures induced proliferation of T10 cells, derived from the T1165 murine plasmacytoma line. A colorimetrically detectable formazan product, obtained by cellular reduction of the tetrazolium compound, 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1), was used as an endpoint for response of clone T10 to added rhIL-11. Positions of the samples and the standards in 96-well microplates affected the precision of this bioassay, which was improved by using 2 microplates where serially diluted sample and standard lines were interleaved and their positions were alternated. The coefficient of variation for this bioassay was less than 8%. This method is suitable for quality control of rhIL-11 because of its simplicity, reproducibility, and accuracy.