The present invention provides vaccines and a means of vaccinating a vertebrate so as to prevent or control specific T cell mediated pathologies, including autoimmune diseases and the unregulated replication of T cells. The vaccine is composed of a T cell receptor (TCR) or a fragment thereof corresponding to a TCR present on the surface of T cells mediating the pathology. The vaccine fragment can be a peptide corresponding to sequences of TCRs characteristic of the T cells mediating said pathology. Such a peptide can bind to conventional antigens complexed to MHC antigen presenting cells or to superantigens. Means of determining appropriate amino acid sequences for such vaccines are also provided. The vaccine is administered to the vertebrate in a manner that induces an immune response directed against the TCR of T cells mediating the pathology. This immune response down regulates or deletes the pathogenic T cells, thus ablating the disease pathogenesis. The invention additionally provides specific β-chain variable regions of T cell receptors, designated Vβ3, Vβ4, Vβ14 and Vβ17, which are associated with the pathogenesis of autoimmune diseases, such as rheumatoid arthritis (RA) and multiple sclerosis (MS). Also provided are means to detect, prevent and treat RA and MS. Methods of administering DNA or RNA encoding the polypeptides useful as vaccines of the present invention into the tissue cells of an individual is also provided.