Subgroup-specific antigenic marker on immunoglobulin lambda chains: identification of three subtypes of the variable region

Three distinct classes of human k light polypeptide chains have been detected immuuochemically (1). The three antigenic types correspond to the three basic variable sequences designated as ki, kii and kiii (2). In previous reports (3, 4) we described two specificity region subgroups of human λ chains tentatively called (St+) and (St-), differing in antigenic determinants localized on the variable (V) or NH2- terminal region of the λ molecule. In the course of studies on the delineation of the (St-) subgroup with various antisera, several rabbit antisera were encountered which showed differences among (St-) type Bence Jones proreins and λ chains of myeloma proteins in immunodiffusion analysis. Similar differences were found for the (St-) type proteins of normal serum. The antigens involved correlate with certain structures of the V region of the λ polypeptide chain. Myeloma proteins and Bence Jones proteins were isolated and typed with respect to subgroup (4).