Provided are compositions and methods for promoting tolerance to auto-immune antigens. In general the compositions include quantum dots (QDs) that are in association with auto-immune peptide antigens. It is shown that QDs can be used to generate immunological tolerance by controlling the density of self-antigen on QDs. Peptide-QDs rapidly concentrate in draining lymph nodes, and co-localize with macrophages expressing scavenger receptors involved intolerance. Treatment with peptide-QDs reduces disease incidence 10-fold. The degree of tolerance and the underlying expansion of regulatory T cells correlates with the density of myelin molecules presented on QDs such that higher numbers of tolerogenic particles displaying lower levels of self-peptide are more effective for inducing tolerance than fewer particles each displaying higher densities of peptide. The disclosure is therefore relevant to promoting tolerance to antigens that are involved in a variety of autoimmune disorders.
