HSV-1 infection of DCs leads to CD18 activation and increased adhesion to ICAM-1. (A) At the indicated time points after infection, flow cytometric analyses of mock-infected DCs (white columns), HSV-1 UV-infected (gray columns), and HSV-1–infected DCs (black columns) were performed with the CD11/CD18 activation-specific antibody mAB24. Concomitantly with CYTIP down-regulation, β2-integrins undergo affinity maturation in HSV-1–infected DCs. Shown is the mean fluorescence intensity as calculated by substraction of isotype fluorescence from mAB24 fluorescence. (B) Four hours after infection, DCs were allowed to adhere to ICAM-1–Fc-coated 96-wells for 45 minutes. After gentle washing, adherence was quantified by measuring the β-glucuronidase activity of the cells. HSV-1–infected cells adhere significantly stronger compared with mock-infected control cells. Error bars represent ± SD. ***P < .001. **P < .01. *P < .05. Experiments were repeated at least 3 times independently. ICAM-1–adhesion experiments were performed in quadruplicate.