An immunoglobulin promoter displays cell-type specificity independently of the enhancer.

Recent studies in which cloned immunoglobulin genes were introduced into cultured cells have produced two significant findings. First, the genes are expressed after transfection into lymphoid cells but not non-lymphoid cells. Second, transcription of an immunoglobulin gene requires, in addition to the promoter region, an enhancer element located downstream of the transcription start site. These findings raise the question of whether it is the promoter or the enhancer region that is responsible for the observed cell-type specificity. It has, in fact, been shown that immunoglobulin enhancers function only in lymphoid cells. We show here that the promoter for an immunoglobulin kappa light-chain gene also is strongly specific for lymphoid cells. Our result reemphasizes the importance of promoters relative to enhancers in determining which cells express which genes.