False positive results in class-specific rheumatoid factor (RF) assays due to interaction between RF and Fc fragments of anti-immunoglobulin indicator reagents
A recently developed, simple immunological method, diffusion-in-gel ELISA, has been adapted for class-specific determination of rheumatoid factor (RF). Evidence was obtained of an analytical error due to interaction between RF and antigenic determinants on the Fc part of the indicator immunoglobulin (Ig) molecules used. This was eliminated by replacing the usual indicator reagent, complete Ig mole
