Method of Treatment and Prophylaxis of Diseases Related to Amyloid Deposition Using IGM

A pharmaceutical composition comprising IgM, at least a portion of which binds specifically to Aβ 1-42, where the IgM is prepared from starting material comprising immunoglobulins and other substances by

• a) adjusting the pH of the starting material to form an intermediate solution comprising dissolved immunoglobulins,
• b) adjusting the intermediate solution of step a) to conditions of pH, temperature, and caprylate concentration such that a first precipitate and a first supernatant comprising immunoglobulins are formed,
• c) separating the first supernatant from the first precipitate,
• d) incubating the first supernatant under conditions of time, pH, temperature and caprylate concentration such that a second precipitate and a second supernatant comprising immunoglobulins are formed,
• e) separating the second supernatant from the second precipitate,
• f) contacting the second supernatant with a first anion exchange resin under conditions of pH and ionic strength such that substantially none of the immunoglobulin G or immunoglobulin M is bound to the first resin but immunoglobulin A and other substances are bound to the first resin,
• g) separating a fraction containing substantially all of the immunoglobulin G and immunoglobulin M from the result of the previous step,
• h) contacting the immunoglobulin G and M with a second anion exchange resin under conditions of pH and ionic strength such that substantially none of the immunoglobulin G is bound to the second resin but immunoglobulin M and other substances are bound to the second resin,
• i) eluting IgM from the second anion exchange resin column with a buffered solution having a conductivity in the range of that found in a solution of at least 100 mM sodium chloride,
• j) applying the IgM to a gel filtration resin and recovering the IgM,
• k) applying the IgM to an affinity resin comprising immobilized antigens A and B, and
• l) recovering the IgM.