In mammals, lysozyme has been shown to be synthesized in and secreted into the blood by mononuclear phagocytes, particularly macrophages (19) and following antigenic stimulation of the immune system, the level of serum lysozyme increases significantly, for example in rabbits infected with Trichinella spiralis (20) and in the serum and urine of a dog with acute myeloid leukemia (21). This evidence concerns the gene LYZ and acute myeloid leukemia.