PRTN3 is a serine protease enzyme expressed mainly in neutrophil granulocytes. The inflammatory cells involved include neutrophil granulocytes and macrophages, two types of white blood cells. These organs house typical immune cells (granulocytes, lymphocytes and plasma cells). The chondrostean kidney is an important hemopoietic organ; where erythrocytes, granulocytes, lymphocytes and macrophages develop. Activated PMN secrete chemokines, IL-8 particularly, to attract further granulocytes and stimulate phagocytosis. High concentrations of eosinophil granulocytes are in blood. When confronted with bacteria, white blood cells, or neutrophil granulocytes, behave like predatory spiders. Phagocytosis of antibody-coated platelets by human granulocytes. The lifespan of neutrophil granulocytes is quite short. The principle of their operation is based on the detection of granulocytes esterases, including leukocytes. Some instruments can also count immature granulocytes and nucleated red blood cells. Post-chemotherapy, IL-3 application reduces chemotherapy delays and promotes regeneration of granulocytes and platelets. It does not however obstruct the phagocytic or other defense roles of granulocytes. These immature granulocytes are seen in peripheral blood smears. Eosinophils are terminally differentiated granulocytes found in most mammals.