Abstract: The polysulfone hollow fiber membrane provided by the present invention can prohibit bacteria, bacilli, viruses and the like, and is therefore useful, besides as an industrial filter for water purification, as a membrane for body fluid filtration or condensation. In particular, the polysulfone hollow fiber membrane is, being excellent in removing .beta..sub.2 -MG, markedly useful as a membrane for treating body fluid such as hemodialysis and hemofiltration.

Abstract: This invention provides a method for treating blood plasma wherein a hollow fiber membrane which comprises at least a skin layer on one surface of the membrane and also a porous layer inside the membrane is employed. The skin layer of the membrane has micropores with average pore size of 50 to 450 A, and the membrane shows a water permeability of 80 ml/m.sup.2.hr.mmHg or more, and permeabilites for human blood plasma albumin of 85% or more and for human blood plasma immunoglobulin G(IgG) of 80% or more, and a rate of inhibition against human blood plasma immunoglobulin M(IgM) of 40% or more. Use of the above mentioned hollow fiber membrane, which makes it possible to selectively remove immune complex, rheumatoid factors, etc., without decrease in levels of immunological functions, brings excellent effects on therapy of autoimmune diseases.

Abstract: A polyvinyl alcohol (PVA) microporous membrane is disclosed which is prepared by a process which comprises forming a PVA membrane containing fine silica particles therein and substantially extracting said silica particles from said membrane, thereby forming a plurality of micropores therein with an average diameter of 0.01 to 50 microns and a porosity of at least 60%.