Spontaneous and induced adaptive immune responses in Alzheimer's disease: new insights into old observations.

Alzheimer's disease (AD) is the leading cause of dementia in the elderly. Although AD is primarily a neurological disorder distinguished by amyloid β plaques and intracellular neurofibrillary tangles, the immune system can impact the progression of the disease and may be targeted for therapeutic purposes. To date, most studies have focused on innate immune responses of microglia. However, emerging evidence implicates adaptive immune responses by T cells and B cells in the progression of AD. Moreover, the recent approval of an antibody that promotes amyloid β plaque clearance for AD therapy has pinpointed adaptive immunity as a fertile ground for the design of novel therapeutic approaches. Here, we highlight key studies delineating T cell and B cell responses in human AD and mouse models of AD, identify open questions on the specificity, development and impact of these responses and discuss outlooks for future studies and novel therapeutic avenues.