"Tolerosomes" are produced by intestinal epithelial cells

The development of immunological tolerance to orally fed antigens depends o n the sampling, processing and transportation events followed in the intest inal epithelium. We present here a description of a "tolerosome": a supra-m olecular, exosome-like structure assembled in and released from the small i ntestinal epithelial cell. The tolerosome is a approximate to 40 nm large v esicular structure that carries MHC class II (MHC II) with bound antigenic peptides sampled from the gut lumen. Tolerosomes isolated from serum shortl y after antigen feeding or from an in vitro pulsed intestinal epithelial ce ll line are fully capable of inducing antigen specific tolerance in naive r ecipient animals. Purified tolerosomes represent a structure by which fed a ntigens can be efficiently presented to the immune system. Removal of the t olerosomes from serum by ultracentrifugation or absorption of MHC II result s in abrogated tolerance development.