Recombinatorial biases and convergent recombination determine interindividual TCRβ sharing in murine thymocytes.

Overlap of TCR repertoires among individuals provides the molecular basis for public T cell responses. By deep-sequencing the TCR beta repertoires of CD4(+)CD8(+) thymocytes from three individual mice, we observed that a substantial degree of TCR beta overlap, comprising similar to 10-15% of all unique amino acid sequences and similar to 5-10% of all unique nucleotide sequences across any two individuals, is already present at this early stage of T cell development. The majority of TCR beta sharing between individual thymocyte repertoires could be attributed to the process of convergent recombination, with additional contributions likely arising from recombinatorial biases; the role of selection during intrathymic development was negligible. These results indicate that the process of TCR gene recombination is the major determinant of clonotype sharing between individuals. The Journal of Immunology, 2012, 189: 2404-2413.