FBGCs are formed through the fusion of multiple macrophages. When the immune system encounters a large foreign body, such as a splinter, surgical implant, or other indigestible material, macrophages are recruited to the site. When individual macrophages are unable to phagocytose the foreign material, they fuse together to form a larger cell, capable of attempting to sequester the substance. This process is known as cell fusion and involves the coordination of various cytokines and cell surface receptors.
