A, confocal microscopy of C57BL/6 IKDC (CD11cintB220+CD49b+), NK (CD11c-B220-CD49b+), and CDC (CD11chiB220-CD49b-) labeled with anti-IA/IE (red) and anti-CD49b (green) antibodies. Blue, nuclei. B, IKDC, NK, and CDC shown in A were stained by ICS for I-A/E (see legend) or isotype-matched control (shaded histogram) and expression was assessed by FACS. C, BALB/c CD11c+ (including CDC and IKDC) and CD11c- (including NK) splenocytes were incubated 12 h with MCMV-infected or mock-treated fibroblasts. MHC-II expression was assessed by FACS on NK (CD49b+ cells from the CD11c- fraction), IKDC (CD49b+ from the CD11c+ fraction), and CDC (CD11chiCD49b- from the CD11c+ fraction).