Malfunction of Cerebral Microcirculation in Macroglobulinemic Mice

THE natural history of human macroglobulinemia includes transient neurological symptoms ranging from headache to dizziness, dysequilibria, and focal motor weakness.¹⁻³In many cases these symptoms are associated with a rise in serum viscosity and are ameliorated by plasmaphoresis which reduces the concentration of macroglobulin (IgM) and the serum viscosity. These symptoms form a portion of the "hyperviscosity syndrome"¹and are often accompanied by "beading" or the presence of "box-car" deformities in retinal vessels.¹,⁴⁻⁶An experimental model of macroglobulinemia is provided by Balb/c mice, bearing a plasma cell tumor, (MOPC-104E), which secretes large amounts of IgM into the blood stream.⁷,⁸Like their human counterparts¹,⁹,¹⁰these mice display an elevated blood viscosity which is a function of the concentration of IgM in the plasma, and which also depends upon the viscosity of the plasma, and the hematocrit level.⁸Erythrocytes from these mice displayed a marked