On the cover: The cover illustrates the electron density obtained by crystallography at the intermolecular interface for a Fab fragment of the therapeutic Ab eculizumab caught in action while inhibiting its Ag complement C5. Eculizumab is used clinically to treat paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome. Schatz-Jakobsen, J. A., Y. Zhang, K. Johnson, A. Neill, D. Sheridan, and G. R. Andersen. 2016. Structural basis for eculizumab-mediated inhibition of the complement terminal pathway. J. Immunol. 197: 337–344.