Antigenic analysis of rheumatoid factor

Abstract

Papain digestion of human γ globulin yields two main antigenic components, of slow (S) and fast (F) electrophoretic mobility. Recent work has shown that β₂M globulin (γ₁ macroglobulin) contains S but not F antigenic groupings. It also contains specific groupings which may be called X. Rabbit antisera have been prepared which are specific for S, F and X.

Sheep red cells, `sensitized' with rabbit anti-sheep cell serum as for the Rose-Waaler test, were incubated with rheumatoid arthritis sera. Under appropriate conditions these cells failed to agglutinate when resuspended in saline, but could be agglutinated by anti-γ globulin (S+F), anti-S and anti-X, but not by anti-F. Cells incubated with normal serum failed to agglutinate. Thus rheumatoid arthritis sera contain a protein possessing the antigenic characteristics of β₂M globulin which specifically coats sensitized sheep cells. This provides further evidence of the antibody nature of rheumatoid factor.