In human autoimmune diseases such as rheumatoid arthritis, Sjögren's syndrome, and multiple sclerosis, it has been clarified that autoreactive T cells play a crucial role in the generation of autoimmune disorders. Immunohistochemical studies have shown that most infiltrating lymphocytes are CD4 positive alpha beta T cells. Recent studies with polymerase chain reaction (PCR) provides evidence about the T cell receptor (TCR) V beta and V alpha genes on their T cells. Sequence analysis of the complementarity determining region 3 (CDR3), which is a central portion for recognition of antigens by T cells, indicates some conserved amino acid motifs, supporting the notion that infiltrating T cells recognize relatively few epitopes on autoantigen.