Analysis of the DC phenotype. Immature DCs or DCs matured with different TLR ligands were phenotypically analyzed by flow cytometry. Stainings were done with monoclonal antibodies recognizing CD1a, CD83, and MHC class I and class II. Gray histograms represent stainings with the indicated antibody, black histograms represent the isotype control. The level of surface expression is indicated as mean fluorescence intensity.