The capsule polysaccharide of several Neisseria meningitidis serogroups can be modified by O-acetylation in vivo. As capsule expression is a major determinant of the interaction between N. meningitidis and human dendritic cells (DCs), the influence of the capsule polysaccharide acetylation status on activation of DCs was investigated. For serogroup C, W-135 and Y, mutations resulting in a lack of capsule acetylation did not interfere with recognition and phagocytosis of N. meningitidis, induction of DC maturation or triggering of cytokine release. Therefore, acetylation of the meningococcal capsule does not modify the activation of dendritic cells by this pathogen.