Serum and serum fractions from patients with rheumatoid arthritis have been subjected to anion exchange chromatography on diethylaminoethyl cellulose. The rheumatoid factor activity was clearly separated from the bulk of the gamma globulin by virtue of the anomalous behavior of macroglobulins on this column.
Purification of rheumatoid factor by precipitation with fraction II, resolution in 4 M urea, and two successive fractionations on an anion exchanger yielded a highly active preparation consisting of approximately 95 per cent 19S gamma globulin with no detectable amount of 7S contaminant.
Evidence was obtained for the existence of two factors by cation exchange chromatography (carboxymethyl cellulose) of rheumatoid serum and of macroglobulin previously separated by anion exchange chromatography. One factor (factor I) agglutinated sensitized sheep cells and latex particles and also precipitated with human fraction II. The second (factor II) agglutinated latex partides and precipitated with fraction II but did not agglutinate sensitized sheep cells.
A substance with the properties of factor II was demonstrated in two of four normal sera by cation exchange chromatography. It was suggested that the agglutination of latex particles and precipitation with human fraction II, observed in the case of certain abnormal sera, may be due to elevated concentrations of factor II.