Evaluation and optimization of variables in immunofixation electrophoresis for the detection of IgG paraproteins.

We examined different antisera and varying serum dilutions for their effects on the sensitivity of immunofixation electrophoresis (IFE) for detecting and characterizing serum IgG paraproteins. Different antisera reacted unequally with a single paraprotein and conversely, a single antiserum reacted unequally with several different paraproteins. The dilution of serum was extremely important; the adoption of a single dilution for all sera could result in failure to detect low-concentration or poorly immunoreactive paraproteins. While the application of a standardized amount of paraprotein is recommended, it must be emphasized that no single antiserum can be relied on to provide unequivocal detection of all paraproteins of that particular isotype.