Peripheral blood cells are the cellular components of blood, consisting of red blood cells (erythrocytes), white blood cells (leucocytes), and platelets, which are found within the circulating pool of blood and not sequestered within the lymphatic system, spleen, liver, or bone marrow. Peripheral blood cells are the cellular components of blood, consisting of red blood cells (erythrocytes), white blood cells (leucocytes), and platelets, which are found within the circulating pool of blood and not sequestered within the lymphatic system, spleen, liver, or bone marrow.