The reaction of rheumatoid factor with animal gamma-globulins: quantitative considerations

Bis-diazotized benzidine has been conjugated to the γ-globulins of three species to produce soluble aggregates and insoluble aggregates for use in the study of the rheumatoid factor. Soluble aggregates have proved useful in the study of the interaction of rheumatoid factor with human and rabbit γ-globulins by agar diffusion methods. Insoluble complexes have provided a method for the absorption and quantitative determination of the rheumatoid factor capable of reacting with the γ-globulins of various species.

The rheumatoid factor in three sera extensively studied has been demonstrated to consist of a heterogeneous entity, which reacts in toto with human γ-globulin and moieties of which also react with rabbit, bovine and equine γ-globulins. The extent of cross-reactivity with rabbit and bovine γ-globulins has been demonstrated to differ from one serum to another.

The characteristics of the reactivities of rheumatoid factor make it seem most probable that the rheumatoid factor is an antibody to denatured human γ-globulin possessing cross-reactivity with other mammalian γ-globulins.