A new assay to measure monoclonal antibody-dependent complement or macrophage-mediated tumor growth inhibition

A new in vitro assay has been developed to measure the inhibition of tumor growth by antibody and complement or by antibody and macrophages. Tumor cells (1 X 10(5) cells) or a mixture of tumor cells (1.5 X 10(4) cells) and macrophages (1.5 X 10(5) cells) are immobilized in a 1 microliter agarose droplet. Antibody is added to the medium bathing the agarose droplet. Complement is also added to wells containing droplets with tumor cells alone. The area covered by tumor cell monolayer is measured non-destructively from day 0 to day 7 with a split image tracing device. Cell growth is expressed by the increase in the square root of the measured area. This assay does not require isotopes and can be used to test tumor cells freshly dissociated from solid tissues. It permits cell-cell interactions which may change the sensitivity of tumor cells to various treatments. The extended period of observation allows the testing of multiple treatments. Surviving cells can also be recovered for further study. This assay may be useful for testing the efficacy of monoclonal antibody treatment on solid tumors.