The antigenic relationship between isolated guinea pig 7 S γ1 and γ2 antibodies has been examined. The two γ-globulins cross-react when studied with rabbit antisera to whole guinea pig serum in immunoelectrophoresis and Ouchterlony plates. Absorption of rabbit antisera with the slow fragment of guinea pig γ-globulin, obtained by starch block electrophoresis of papain digest, removes this cross-reactivity. It is concluded that the known differences in biologic activities of these two types of γ-globulins must be due to different structures of the H chain.
Isolated guinea pig antibodies of various antihapten specificities show consistent differences in their immunoelectrophoretic patterns with respect to mobility and number of precipitation arcs observed. Some of the differences have been shown to reside in the slow fragment. However, no qualitative antigenic differences have thus far been shown by absorption studies of the rabbit antisera used.