Changes of nuclear Rel proteins during maturation of epidermal mouse Langerhans cells correspond to those in human dendritic cells.

(A) Immunoblots of nuclear proteins from freshly explanted Langerhans cells (immature phenotype, day 0, lane 1), Langerhans cells cultured for 24 hours (intermediate phenotype, day 1, lane 2), and maturated Langerhans cells (mature phenotype, day 3, lane 3). (B) EMSAs performed with nuclear proteins. The protein extracts were prepared from freshly explanted Langerhans cells (day 0, lane 1), Langerhans cells cultured for 24 hours (day 1, lane 2), and mature Langerhans cells cultured for 3 days (day 3, lane 3). As a control for DNA binding specificity, an excess of unlabeled κB-specific probe was added to nuclear extracts from mature Langerhans cells (C, lane 4). The 3 detectable κB-specific DNA binding complexes are designated I-III (see below). The asterisk indicates an additional complex of unknown composition. (C) Supershift EMSAs with nuclear proteins from freshly explanted Langerhans cells (day 0, lanes 1-5), Langerhans cells cultured for 24 hours (day 1, lanes 6-10), and mature Langerhans cells after 3 days in culture (day 3, lanes 11-15). For supershift EMSAs, 1 μl of each of the Rel protein–specific antibodies was added to the extracts as indicated. The 3 detectable κB-specific DNA complexes are composed of p50 homodimers (III), RelB/p50 heterodimers (II), and p65/p50 and, probably, p65/c-Rel heterodimers (I).