Abstract: A method for treating a blood which comprises:separating the blood withdrawn from a patient's body with a first membrane into a condensed blood fraction containing human blood plasma immunoglobulin M, and a plasma fraction; separating the plasma fraction with a second membrane into low molecular weight protein and high molecular weight protein containing human blood plasma immunoglobulin G; and mixing the condensed blood and the low molecular weight protein with a substitute liquid to return the combined liquid into the patient's body; said first and second membranes containing specific sizes of micropores uniformly distributed on at least one surface of the membrane, and having a specific permeability of albumin and specific permeability of human blood plasma immunoglobulin M or G. The method and apparatus specifically can remove only a harmful antibody from a positive patient in a crossmatch test after DST, whereby a transplantation surgery of a living-related kidney can be safely carried out.

Abstract: A method for treating blood uses a tubular body fluid passageway member at least part of which is made of a flexible material, an outer tubular member which is made of a nonflexible material and contains said tubular body fluid passageway member hermetically enclosed therein, a pressure detecting member for monitoring the pressure of the flowing body fluid by means of a fluid filled in the hermetically closed space between the outside surface of said tubular body fluid passageway member and said outer tubular member without substantial contact of the body fluid with air, and a body fluid filtering member comprising a filter. The method is especially useful for non-anticoagulant hemodialysis.