<s>[INST] Pharmaceutical companies developing antibodies for various diseases currently use many mice to make the antibody producing cells. These mice are typically irradiated to suppress their immune systems, and then injected with human cancer cells or other cell types. The human cells are responsible for producing the antibodies that the mice are unable to produce naturally. Antibodies produced from genetically modified mice are directed against human targets. To avoid graft versus host reactions, the mice are further genetically modified to match certain receptors on their T-cells with human receptors. The use of mice with suppressed immune systems can be replaced with a human in vitro system.[/INST]