Evidence for Anti-Gm(a) Antibody in γA Immunoglobulins. ∗

Summary

A serum is described in which anti-Gm(a) activity with characteristics of that found in non-rheumatoid patients was found to have certain unique properties. Most but not all activity was removed by reduction with 0.1 M β mercaptoethanol. Sephadex and DEAE cellulose chroma tography excluded anti-Gm (a) activity from the 7S γG globulins. Studies with sucrose density gradients indicated major anti-Gm (a) activity in a position intermediate between the 19S and 7S immunoglobulins, with an S rate estimated to be between 11.0 and 11.8. Absorption studies showed selective removal of anti-Gm(a) activity from this serum by anti-γA antisera. This evidence supports the contention that anti-Gm activity resides in the γA globulins. The finding of such activity in multiple immunoglobulin classes is in keeping with the concept that anti-Gm agglutinators of this type are antibody in nature.