Abstract
The region on the [human] L chain molecule responsible for expression of the .kappa. and .lambda. antigenic determinants was determined by comparative immunochemical analyses of intact Bence Jones proteins and naturally occurring or enzymatically derived fragments of Bence Jones proteins that lacked extensive portions of the V [variable] region or part of the C [constant] region. The reactivity of these fragments with numerous antisera having specificity for L-chain antigenic determinants indicated the essentiality of the intact L polypeptide chain for expression of the .kappa. and .lambda. antigenic determinants. The conformational dependency of the .kappa. and .lambda. antigenic determinants was also evidenced by denaturation-renaturation studies on .kappa. and .lambda. chains. The V domain, C domain and interdomain switch region contribute to the expression of .kappa. or .lambda. antigenicity and to certain isotypic and allotypic specificities.