Immunological Studies of Human Γ-globulin

Two major antigenic fragments were obtained from various purified gamma-globulin preparations after papain treatment. One, the F component, had a mobility faster than the original gamma-globulin and the second, the S component, had a slower mobility. Similar F and S components were also obtained with certain homogeneous myeloma proteins which were closely related to gamma-globulin immunologically. Additional minor antigenic components were detected with certain antisera. The technique of immunoelectrophoresis was particularly useful for bringing out the different antigenic constituents obtained after papain treatment. The F and S components as well as a midfraction were isolated by chromatography on DEAE-cellulose. These were immunologically homogeneous and could be utilized to absorb F and S antibodies from various antisera. The relative amount of F and S antibodies varied in different antisera from individual rabbits immunized with whole gamma-globulin. Whole gamma-globulin was separated by zone electrophoresis into a fast migrating and a more slowly migrating fraction. Each of these gave rise to F and S components after splitting with papain. The F components of the two gamma-globulins were similar in mobility, while the S components showed marked mobility differences although antigenically they were very similar. The mobility differences of the parent gamma-globulin appeared to be primarily related to the differences in the S component. Certain antisera against pathological gamma-globulins were found to give double lines with a wide variety of gamma-globulin preparations in agar diffusion. These were shown to be related to the F and S antigenic determinants of gamma-glubulin. This relationship was evident by a number of procedures utilizing both Ouchterlony plate techniques and immunoelectrophoresis. The question of whether these findings indicate heterogeneity of gamma-globulin in relation to the F and S antigenic components, or whether different antigenic groups on one molecule can give rise to separate lines in certain instances, is discussed.