Present difficulties and future promise of MHC multimers in autoimmune exploration.

Class I tetramers have been used to track cytotoxic T cells during bacterial and viral infections. During the past year, the use of such molecules has revealed important information about the role of CD8(+) T cells in autoimmune diabetes. Furthermore, class II multimers have been produced and successfully used to stain autoreactive CD4(+) T cells from patients with rheumatoid arthritis or Borrelia-burgdorferi-induced Lyme arthritis.