Abstract: The apparatus includes a peristaltic pump for withdrawing whole blood from a patient, a device for centrifuging the blood to separate plasma from the whole blood, a plasma treatment chamber for receiving the plasma, a vehicle positioned within the chamber and having an immunoadsorbent agent fixed thereon to interact and bond with an immunological reactant carried by the plasma that is passed through the chamber for removing the immunological reactant from the plasma, tubings connected to recombine the substantially immunological reactant free plasma with the remainder of the whole blood and a peristaltic pump for returning the recombined whole blood to the patient. In one plasma treatment chamber, the vehicle is defined by a spiral coiled membrane which has an immunoadsorbent agent fixed thereon. Each convolution of the spiral is spaced from an adjacent convolution and the coil is positioned within the chamber so that plasma flows through the space between the convolutions of the spiral coiled membrane.