Microheterogeneity of paraproteins. I. Diagnostic value of isoelectric focusing followed by immunoblotting.
Isoelectric focusing (IEF) in thin-layer polyacrylamide gels followed by immunoblotting on nitrocellulose membranes is presently the most sensitive method in the routine detection of IgG paraproteins. With this technique, immunoglobulin class and light chain composition can be as reliably identified as in immunoelectrophoresis. The problem of firm adherence between IEF polyacrylamide gels and nitrocellulose membranes can be overcome by brief incubation in sodium dodecyl sulfate. After isoelectric focusing, IgG paraproteins display a characteristic pattern of limited electrophoretic heterogeneity. This pattern is easily recognized even in the few cases with a constant tendency to aggregate under IEF conditions and in the surprisingly high percentage of paraproteins with very alkaline isoelectric points in which it is altered due to a cathodal collection effect. It is independent of the total amount of IgG in serum and remains stable intraindividually over extended observation periods. On the other hand, there is a very high degree of interindividual variability while common paraprotein characteristics still remain recognizable.
Schipper
H I
HI
Department of Neurology, University of Goettingen FRG.
Bertram
G
G
Kaboth
U
U
D000180:Acrylic Resins; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D007158:Immunologic Techniques; D007525:Isoelectric Focusing; D010266:Paraproteins / Q000032:analysis*
D000180:Acrylic Resins; D007074:Immunoglobulin G; D010266:Paraproteins; C016680:polyacrylamide gels