CLONAL PREVALENCE OF T-CELLS INFILTRATING INTO THE PANCREAS OF PREDIABETIC NONOBESE DIABETIC MICE

The non-obese diabetic (NOD) mouse spontaneously develops T-cell-media ted autoimmune insulitis, We analyzed the clonotypes of T cell infiltr ates of the NOD mouse islets using a new method we have developed rece ntly, which consists of RT-PCR amplification of the CDR3 region of the TCR beta chain mRNA and subsequent single-strand conformation polymor phism (SSCP) analysis, NOD mice of 10-32 weeks of age were shown to ac cumulate oligoclonal T cells in the pancreas, To examine whether each T cell clone stays in a small area of the pancreas or spreads over the whole pancreas, a pancreas was divided into two pieces, which were th en subsequently analyzed in a pair by the above PCR-SSCP method, When a pair produces common bands with the same mobility in SSCP gel, they are likely to represent the presence of the same T cell clones between these two parts of the pancreas, Aged mice (24-32 weeks old) with sev ere insulitis obviously produced more common bands for most of the V-b eta subfamilies than younger mice (10 weeks old) with only periinsulit is, DNA sequencing verified that these common bands have the same TCR junctional sequences, suggesting that they were derived from the same T cell clones, These results suggest that clonal prevalence of T cells infiltrating into the pancreas occurs in the late stage of insulitis development and that a limited number of T cell clones finally predomi nate over the whole pancreas.