A container having a flexible wall receives a continuous flow of a biological fluid that includes a target antigen and emits a continuous flow of the biological fluid at least partially depleted from the target antigen. The container further comprises a compartment with magnetic beads coupled to an affinity marker that binds the target antigen, and the target antigen is separated from the biological fluid using a magnetic force and an automatic mechanical force, wherein at least one of the magnetic force and automatic mechanical force is transmitted through the flexible wall.