THE BINDING OF SYNOVIAL TISSUE-DERIVED HUMAN MONOCLONAL IMMUNOGLOBULIN-M RHEUMATOID-FACTOR TO IMMUNOGLOBULIN-G PREPARATIONS OF DIFFERING GALACTOSE CONTENT

There are several sites on IgG Fe that have been reported to be the ep itopes for binding rheumatoid factors (RF). It is now established that there are alterations in the oligosaccharides on IgG from patients wi th rheumatoid arthritis and it has been suggested that these changes m ay enhance immune complex and cryoglobulin formation. We have used a s eries of IgG preparations differing in their content of oligosaccharid e chains lacking galactose from 18 to 86% to determine whether changes in sugar content affect the binding of rheumatoid factor. Five of 16 monoclonal rheumatoid factors prepared from synovial tissue, from pati ents with juvenile or adult rheumatoid arthritis, bound better to IgG which was deficient in galactose. Six of the 16 rheumatoid factors fro m the same patients bound independently of the galactose content. Four of the 16 rheumatoid factors could not be absolutely grouped in this manner but seemed to demonstrate a preference for agalactosyl IgG. One rheumatoid factor bound better to fully galactosylated IgG. There was an association between enhanced binding to galactose-deficient IgG an d monoreactivity and a very strong association between the functional affinity of the rheumatoid factors and the dependent binding.