RHEUMATOID FACTORS FROM PATIENTS WITH RHEUMATOID-ARTHRITIS REACT WITHTRYPTOPHAN-60 AND TRYPTOPHAN-95, LYSINE-58, AND ARGININE-97, ON HUMANBETA-2-MICROGLOBULIN

Objective. To define precise epitopes on human beta2-microglobulin (be ta2m) reacting with polyclonal IgM rheumatoid factors (RF) from patien ts with rheumatoid arthritis (RA). Methods. Ten polyclonal RF were tes ted for their human beta2m epitope-binding specificities using the ent ire 99-amino acid sequence synthesized as overlapping 7-mers in an enz yme-linked immunosorbent assay. Glycine substitution for each residue within RF-reacting linear regions was employed to define major reactiv e sites. Results and Conclusion. Major beta2m residues contributing to RF reactivity were tryptophans at positions 60 and 95, lysine at 58, and arginine at position 97.