Development of new hollow fiber membrane macromolecular filters

Newly developed hollow fiber membrane filters made of ethylene-vinyl-alcohol designated as EVAL 2A, EVAL 4A, and EVAL 5A, were tested in vitro and applied clinically. EVAL 2A had the lowest molecular weight cut-off (30% rejection rate for 10(4) dalton dextran and 90% rejection rate for 10(5) dalton dextran); sieving coefficients (SC) of 0.78 for albumin, 0.59 for IgG, and almost 0 for IgM indicate its usefulness for separation of IgG from albumin when the recirculation flow on the filter was introduced. EVAL 4A and 5A showed higher cut-off levels (25% rejection of 10(5) dalton dextran and 80% rejection rate for 2 X 10(6) dalton dextran); SCs for albumin IgG, and IgM were 0.89, 0.83, and 0.24, respectively, indicating their usefulness in the separation of MMs of molecular size greater than IgG. IgM type cold agglutinin antibody (CAA), IC, and RF were effectively removed by these filters from CAA induced hemolytic anemia or rheumatoid vasculitis patients. Using recirculating flow to prevent filter plugging, one EVAL unit was found to be sufficient to treat 2-3 L plasma. These filter properties demonstrate the possible clinical application of EVAL filters for selective MM removal, when specific MM removal is indicated for the treatment of specific diseases.