Exploiting M cells for drug and vaccine delivery

The specialised antigen sampling M cells represent an efficient portal for mucosal drug and vaccine delivery. Delivery may be achieved using synthetic particulate delivery vehicles including poly(DL-lactide-co-glycolide) micr oparticles and liposomes. M cell interaction of these delivery vehicles is highly variable, and is determined by the physical properties of both parti cles and M cells. Delivery may be enhanced by coating with reagents includi ng appropriate lectins, microbial adhesins and immunoglobulins which select ively bind to M cell surfaces. Live attenuated microorganisms are also suit able as vaccines and mucosal vectors and many, including Salmonella typhimu rium, innately target to M cells. After cell surface adhesion, delivery veh icles are rapidly transported across the M cell cytoplasm to underlying lym phoid cells and may subsequently disseminate via the lymphatics. Further de finition of M cell development and function should permit exploitation of t heir high transcytotic capacity for safe and reliable mucosal delivery. (C) 2001 Elsevier Science B.V. All rights reserved.