We have recently shown that the ability of microglia to effectively fight off aggregated β‐amyloid plaque formation and cognitive loss in transgenic mouse models of Alzheimer's disease (Tg‐AD), is augmented in response to T‐cell‐based immunization, using glatiramer acetate (GA). The immunization increases incidence of local CD11c⁺ dendritic‐like cells. It is unclear, however, whether these dendritic cells are derived from resident microglia or from the bone marrow. To determine the origin of this dendritic‐cell population, we used chimeric mice whose bone marrow‐derived cells express a transgene that allows the cells to be specifically ablated by diphtheria toxin. We show here that T‐cell‐based immunization of these mice, using GA, induced the recruitment of bone marrow‐derived dendritic cells. Depletion of the dendritic cells by systemic injection of diphtheria toxin resulted in significantly increased formation of amyloid plaques. Thus, recruitment of bone marrow‐derived dendritic cells evidently plays a role in reducing plaque formation in a mouse model of Alzheimer's disease.