Two Boston-based researchers have managed to re-train the immune system to ignore antigens that trigger an autoimmune reaction, alleviating symptoms of multiple sclerosis (MS) and type 1 diabetes in a mouse model. Their study, “Engineered erythrocytes covalently linked to antigenic peptides can protect against autoimmune disease,” appeared in a leading medical journal, Proceedings of the Academy of Sciences (PNAS). The researchers, Hidde Ploegh of Boston Children's Hospital and Harvey Lodish of the Whitehead Institute for Biomedical Research, attached pieces of disease-specific proteins to red blood cells and then transferred these cells back into a mouse model of MS. The pieces of protein led to what is called the induction of tolerance, in which the immune system is “taught” to ignore antigens that could otherwise trigger an inappropriate response. “Essentially what we’re doing is hijacking the red blood cell clearance pathway, such that the foreign antigen masquerades as the red blood cells’ own, such that these antigens are being tolerated in the process,” graduate student Novalia Pishesha said in a press release. This strategy reduced MS and type 1 diabetes symptoms in the mice. Importantly, even a single injection before disease onset could produce similar results and prevent the development of further symptoms. The researchers explained that red blood cells are particularly well-suited to carry molecules to different parts of the body because they can quickly access almost all tissues. Moreover, they are quickly recycled — every month in mice and every four months in humans — without triggering an immune response. “This is a very promising step in the development of therapies for autoimmune diseases,” said Lodish, a biological engineering professor at MIT. “If this type of response is also true in humans, then it could make a lot of these therapies possible for these diseases and similar conditions.” Autoimmune diseases develop when the body’s immune system mistakenly attacks its own cells. Some 23 million Americans are believed to have autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, type 1 diabetes and MS.