Through the use of a variety of antisera to isolated myeloma proteins, four subgroups of 7S γ-globulin type proteins were readily distinguished. The first, the Vi subgroup, consisted of ten of 64 myeloma proteins studied. The second, the We group, contained the majority of myeloma proteins. The third, the Ge subgroup, included three of 50 myeloma proteins. The fourth remains ill-defined and appears heterogeneous.
Counterparts for both the Vi and the Ge subgroup, were found in the Fr II γ-globulin and in the normal γ-globulin of all of a large number of individual sera studied.
The unique antigenic character of both groups was localized to the H chains, although different determinants were involved for different antisera. An essential role of intact disulfide bonds was apparent with certain rabbit antisera.
In addition to the special antigenic characteristics, the Ge subgroup showed in each instance a fast mobility for the F fragments produced by papain which was not found for other myeloma proteins.