Macrophages are a type of white blood cell that play a vital role in fighting infections. Like many other cells of your immune system, they are produced in the bone marrow and travel through the blood to your tissues. Macrophages are found mainly in the liver, spleen, and lymph nodes. Materials: Plush from all new materials. Stuffed with polyester fiber fill. Surface washable: sponge with water & soap, air dry.