The spleen is the biggest lymphoid organ of adult human beings, which is situated in the upper far left part of the abdomen, to the left of the stomach. The size and shape vary between people, but it’s commonly fist-shaped, brownish in color and about 4 inches long. In spite of the protection from ribs on the left side, it can be damaged by a severe hit to the stomach area. The spleen keeps its hematopoietic function before red bone marrow starts to take over the corresponding work. The spleen in the adult body has three main functions: storing immune cells, filtering blood and storing blood. The immune cells in the spleen (mainly B cells and T cells) play an essential role in the immune response of the body. The macrophages residing in spleen can ingest microorganisms such as bacteria, fungi, and viruses, and remove the unwanted red blood cells, which acts as a blood filter. Additionally, the spleen works as a reservoir of different elements of the blood, especially white blood cells and platelets. If the spleen can not work properly, it may cause some problems like anaemia, increased risk of infection or bleeding. Some of the target molecules expressed on spleen tissue has been used in detection.