CDR3 SIZE SPECTRATYPING AND SEQUENCING OF SPECTRATYPE-DERIVED TCR OF SPINAL-CORD T-CELLS IN AUTOIMMUNE ENCEPHALOMYELITIS

To characterize the nature of autoimmune disease-inducing T cells in t he target organ, oligoclonal expansion of spinal cord T cells of Lewis rats with experimental autoimmune encephalomyelitis (EAE) was examine d by complementarity-determining region 3 (CDR3) size spectratyping. I t is known that TCR of in vitro-established myelin basic protein-speci fic T cell clones and lines have a short CDR3 and that the amino acid sequence in this region is highly preserved. On the basis of these fin dings, we analyzed 22 spectratypes of the TCR beta-chain (V beta 1-20) . Among them, only V beta 8.2 and V beta 17 showed oligoclonal expansi on of TCR with a short CDR3 at the early stage of EAE. More interestin gly, the spectratype profile of V beta 8.2 seen at the early stage was preserved throughout the course of EAE, whereas that of V beta 17 bec ame more diverse at the peak stage of the disease. Analysis of nucleot ide and predicted amino acid sequences of V beta 8.2 CDR3 derived from the spectratypes revealed that the clones with CASSDSSYEQYFGPG, which is one of the representative sequences of encephalitogenic T cell clo nes, constituted the predominant population not only at the early stag e but also at the peak and recovery stages (71, 71, and 60%, respectiv ely). These findings imply that although the phenotype of T cells in t he target organ diversifies as the autoimmune disease progresses, dise ase-associated TCR spectratype(s) are preserved throughout the course of the disease. Thus, CDR3 size spectratyping is a powerful tool for t he screening of disease-inducing T cells in an autoimmune disease of u nknown pathomechanism.