Selective removal of plasma cryoglobulins in cryoglobulinaemia.

Cryoglobulins were removed from the plasma of two patients with mixed cryoglobulinaemia (IgM(k)-IgG type) associated with severe membrano-proliferative glomerulonephritis and angiitis. The removal of about half the circulating cryo-Igs ('cryo-Igpheresis') was followed by a brisk rebound in cryo-Igs due to the rapid synthesis rate of monoclonal IgM(k) with anti-IgG activity. 'Cryo-Igpheresis' + cyclophosphamide treatment suppressed the rebound of cryo-IgGs, but not that of the cryo-IgMs. This differential effect was due to decrease of the antibody activity of cryo-IgMs. The clinical implications of such changes need further evaluation.