Lineage-restricted function of nuclear factor kappa B-inducing kinase (NIK) in transducing signals via CD40

CD40 signaling in B cells and dendritic cells (DCs) is critical for the dev elopment of humoral and cell-mediated immunity, respectively. Nuclear facto r kappa B (NF-kappa B)-inducing kinase (NIK) has been implicated as a centr al transducing kinase in CD40-dependent activation. Here, we show that alth ough NIK is essential for B cell activation, it is dispensable for activati on of DCs. Such data provide compelling evidence that different intermediar y kinases are used by different cellular lineages to trigger NF-kappa B act ivation via CD40.