Fig. 3.

Identification of somatic V(D)J recombination in lymphocytes. (A) A B cell identified by deletions in Ig light and heavy chain regions. (B) A T cell identified by deletions in the T cell receptor variable loci. This example shows biallelic deletion (copy number = 0), which was observed for select B and T cells and is consistent with nonproductive recombination in overlapping regions. (C) The majority of splenocytes (Lym, n = 105) are classified as either B or T cells, while cortical cells of all ages assessed (Ctx, n = 438) are not. The small population of cortical cells exhibiting deletions in V(D)J loci are artifactually due to low-quality data (see SI Appendix, Figs. S2E and S3C after removal of such instances). *P < 10⁻³⁰.