Primary B cells essentially lack constitutive NF-κB activity

Based primarily on the analysis of B cell lines, mature B cells are considered distinct from non-B cells and immature B cells by having constitutive nuclear NF-κB activity. By their comparison to splenic non-B cells or activated B cells we show here that primary resting B cells lack cell-autonomous NF-κB activity. This finding indicates that the role of the transcription factor in B cells is similar to that in other cells, namely a common mediator of activation and stress signals. Whereas the absence of constitutive NF-κB activity in mature B cells does not argue against a role of NF-κB in B cell development, it does not support the notion of the essential function of the factor in maintaining the unique transcriptional activities in B cells.