T-cell receptor repertoires share a restricted set of public and abundant CDR3 sequences that are associated with self-related immunity

Differences in MHC restriction are associated with more diverse V gene usage. (A) V segment usage of two public CDR3 aa sequences. Weighted mean frequency of V segment usage for each sequence was calculated for different MHC-restricted T-cell groups: CD4⁺ T cells from C57BL/6 mice (left, MHC-II, H2^b haplotype, n = 28); CD4⁺ T cells from C3H.SW mice (second left, H2^b, n = 3); CD4⁺ T cells of C3H.HeSnJ mice (second right, H2^k, n = 2); and CD8⁺ T cells from C57BL/6 mice (right, MHC-I, H2^b, n = 2). V segments are indicated by the color bar on the right. (B) Average correlations in V segment usage calculated between all 289 public CDR3 aa sequences in our C57BL/6 H2^b strain data set and the three other MHC-restricted T-cell groups as in A. Error bars, SEM (see Supplemental Material for details).