CsA and tacrolimus specifically inhibit the expression of SIINFEKL–H-2K^b complexes. DC2.4 cells were incubated with OVA microspheres in the presence (+) or absence (-) of CsA (3000 nM) or tacrolimus (100 nM) for 2 hours, and the expression levels of H-2K^b molecules (A,B) and SIINFEKL–H-2K^b complexes (C,D) were determined by monoclonal antibodies. In panels C and D, the shaded histograms represent DCs that were not incubated with OVA microspheres.