Das T-Zell-Rezeptor-Repertoire bei der Polymyositis

Polymyositis (PM) is an autoimmune disease cased by CD8+ T
lymphocytes that destroy HLA class I-expressing skeletal muscle
fibres. Recently we demonstrated that the autoaggressive T
lymphocytes in PM muscle are clonally expanded. We employed a new
PCR-based method to identify and characterize clonally expanded T
cell populations. The method (CDR3-Spectratyping) relies on te
natural length variation of the third hypervariable region (CDR3)
of the rearranged T cell receptor gene: whereas a polyclonal T cell
population shows a random, Gauss-distributed length variation of
the CDR3, a clonally expanded population has a uniform CDR3 length,
which can be identified as a single band on a sequencing gel. We
analysed matched pairs of cDNA from muscle biopsies and peripheral
blood lymphocytes of PM patients and confirmed previously
identified expanded T cell clones in muscle biopsy specimen.
Moreover, we repeatedly detected identical clonally expanded T cell
populations both in the imflamed muscle tissue and in the
peripheral blood of untreated PM patients.