M cell specific markers in man and domestic animals: valuable tools in vaccine development

M cells play a pivotal role in the induction of immune responses within the mucosa-associated lymphoid tissues. As such, they are frequently studied for the development of mucosal vaccines. Unfortunately, the lack of a universal M cell marker hampers the progress in this field since researchers need species- and tissue-specific markers in order to isolate, identify or target M cells. Depicting the most appropriate M cell marker for the species and tissue under investigation might, however, be complicated by the numerous publications on this topic, often mentioning both positive and negative results for the tested marker. Therefore, this review gives an overview of the specific M cell markers in man and various domestic and laboratory animals. In addition, current state-of-the-art as regards the use of M cell models and markers in mucosal vaccine development is discussed.