MS occurs when the immune system attacks the brain and spinal cord. T cells are the major players in this attack, but recently, researchers have identified a population of regulatory T cells that can suppress disease-causing T cells. A novel treatment strategy involves administering substances that rev up regulatory T cells to suppress the immune attack.

One such strategy that has demonstrated success is the intravenous administration of “CD3 antibodies.” CD3 antibodies have been approved by the US Food & Drug Administration to treat rejection of organ transplantation, and have shown positive results in people with diabetes and arthritis. However, side effects have limited their use. The Harvard team had hoped that giving CD3 antibodies orally might stimulate regulatory T cells located in the digestive system to suppress the immune response, without the whole-body side effects that occur with intravenous administration.

In this study, CD3 antibodies were administered both orally and intravenously in doses of 5, 50 and 500 micrograms to mice either before they developed EAE, an MS-like disease, or during the active course of the disease. Among oral treatments, a low dose of 5 micrograms succeeded in suppressing disease, whereas there was no effect in mice fed 50 micrograms, and disease worsened with the high dose of 500 micrograms. Intravenous doses did not suppress EAE, and the mice appeared ill following treatment. Examination showed that CD3 antibodies were indeed active in the gut of mice fed orally.

This study presents a novel strategy that warrants further study in MS models to ensure its safe and effective development as a treatment strategy for people with MS.