Editorial: Hyperviscosity and immunoglobulin complexes

Plasmapheresis and cold sensitivity of immunoglobulin molecules. I. A study of hyperviscosity, cryoglobulinemia, euglobulinemia and macroglobulinemia vera

There is a close connection between molecular changes of the Ig molecule with sinking temperature and the syndrome of hyperviscosity. The cryoglobulins are usually macroglobulins or complexes between IgM and other immunoglobulin classes. Many of these molecules can also be characterized as euglobulins. The connection between precipitation in the cold and in solutions with low electrolyte content is studied. Data on these connections are presented. The dependence of relative viscosity on the temperature has been investigated in a large number of sera from patients with different diseases. It is clear that most of these cold-sensitive globulins are macroglobulins (IgM). A number of viscosity curves at different temperatures in such sera are given. Also a few sera from patients with IgG myeloma have similar curves. The change in viscosity with lower temperatures implies that relative viscosity has to be determined at 37 degrees C in order to correspond to the condition in the living body. In practice, however, it is usually correct to state that IgM levels above 40 g/l are an indication that plasmapheresis should be considered. The best clinical sign is obtained by ophthalmoscopy. Difficulties with the counting of leukocytes and platelets in electronic counters may be caused by the presence of macroglobulins, usually but not always, cryoglobulins.

Hyperviscosity syndrome

Hyperviscosity syndrome is clinically manifested by oronasal bleeding, retinal hemorrhages, and variable neurological symptoms. It occurs when resistance to flow of blood increases sharply, resulting in impaired transit through the microcirculatory system. The most common cause of hyperviscosity is increased concentrations of gamma globulins, either monoclonal in malignant disease or polyclonal, usually seen with rheumatic disorders. Increased numbers of red blood cells, as in polycythemia vera, can result in viscous blood. Extreme increases in concentrations of mature and immature white blood cells can also produce hyperviscosity. Treatment with plasma exchange is required when the clinical syndrome is symptomatic. Although plasma exchange is not a completely benign procedure, it represents the most effective method of controlling hyperviscosity.

Pathogenic role of a monoclonal IgA (kappa ) anti-IgG paraprotein associated with hemorrhagic diathesis, rheumatoid arthritis, vascular purpura, and acute membranoproliferative glomerulonephritis

Sixteen years earlier a 42-year-old woman with an IgA kappa plasma cell neoplasm presented with bleeding disorder. Her prolonged course was complicated by subsequent development of rheumatoid arthritis, vascular purpura, and an acute membranoproliferative glomerulonephritis (MPGN). The paraprotein and its (Fab')2 fragment showed affinity for a test myeloma IgG2 (lambda ) paraprotein. The patient's serum and the IgA-IgG complex separated by gel filtration did not exhibit cryoprecipitation. The complex also did not dissociate by ultracentrifugation. Electron microscopic and immunofluorescent studies of a renal biopsy sample taken during the episode of nephritis showed subendothelial deposits and a lacy fluorescent pattern strongly positive for IgA and IgG. The same immunoglobulins were eluted from the kidney at postmortem. A low concentration of monoclonal IgA kappa (antibody) and excess unbound polyclonal IgG (antigen) were demonstrated in the patient's serum at the time of MPGN, apparently analogous to the conditions necessary for the induction of experimental immune complex nephritis.

Polyclonal hyperviscosity syndrome

The clinical course of two patients who presented with polyclonal hyperviscosity syndrome is described. Polymerizing IgG rheumatoid factors were isolated from the serum of both patients. The presence of these polymers with their extraordinary rheologic properties was the principal determinant of the abnormal rheological properties of the plasma. Neither patient had a discrete rheumatic disease. In both, a lymphoproliferative syndrome was present with features suggestive of the "pseudolymphoma" of Sjögren's syndrome.