Binding of isolated rheumatoid factors to histone proteins and basic polycations

A fluorimetric immunoassay has been used to assess reactivity of rheumatoid factor (RF) with both histone proteins and other basic polycations (poly-L-lysine, poly-L-ornithine, and protamine) bound to an immobilised tyrosine-glutamic acid polyanionic copolymer. Isolated RF preparations can bind to histone proteins in this assay, notably to H3 and H4 histones, and this activity was always masked in the original whole seropositive sera. Binding of isolated RF was often noted also to the other large-molecular-weight basic polycations.