Modulation of the severity of experimental autoimmune encephalomyelitis bygamma delta T lymphocytes activated by mycobacterial antigens

Immunity to mycobacterial antigens may contribute to the maintenance of sel f-tolerance. Exposure of the immune system to mycobacterial antigen might w ell stimulate the immune system to exert control over unwanted self-reactiv e clones. We demonstrated that in vivo administration of Mycobacterium tube rculosis, PPD, and PPD peptide (180-196) prior to immunization with Myelin Basic Protein (MBP) led to a moderate increase of gamma delta T cells, supp ression of the immune response, and reduction in the severity of Experiment al Autoimmune Encephalomyelitis. The immunosuppression observed is due, at least in part, to the production of Transforming growth factor-beta (TGF be ta) by the gamma delta T lymphocytes.