Methods (300), devices, and systems of processing blood are describes. The method (300) comprises the steps of: obtaining (312) blood from a patient coupled to a single blood processing device to form a closed loop between the patient and the blood processing device； collection (314) bulk mononuclear blood cells from the blood by leukapheresis using the blood processing device in the closed loop； and enriching (316) concurrently target cells separated from non-target cells in the bulk mononuclear blood cells using the blood processing device in the closed loop.
