On the cover: Our virtual model represents events occurring in the T zone of a lymph node, represented by a grid (only a portion is shown). Cells move onto, off of, and around the grid. T cells and dendritic cells enter the lymph node and can move to any adjacent square; T cells can divide, and cells in adjacent squares can interact. Linderman, J. J., T. Riggs, M. Pande, M. Miller, S. Marino, and D. E. Kirschner. 2010. Characterizing the dynamics of CD4+ T cell priming within a lymph node. J. Immunol. 184: 2873–2885.