Mononuclear phagocyte system
In immunology, the mononuclear phagocyte system or mononuclear phagocytic system (MPS), also known as the macrophage system, is a part of the immune system that consists of the phagocytic cells located in reticular connective tissue. The cells are primarily monocytes and macrophages, and they accumulate in lymph nodes and the spleen.
Source: Wikipedia — Mononuclear phagocyte system (CC BY-SA 4.0)