T cells in swine completely rearrange immunoglobulin heavy chain genes.

Porcine thymus contains three independent populations of cells that have rearranged immunoglobulin heavy chain VDJ genes. The first population can be found exclusively in medulla and it consists of existing mature B cells and plasma cells. The second consists of developing B cells characterized by the presence of selected VDJ rearrangement, similar to B cell lymphogenesis in the bone marrow. The third population is entirely unaffected by selection mechanism for productive VDJ rearrangement and represents T lineage cells that rearrange immunoglobulin genes. Transcription of unselected VDJ repertoire is not allowed in T cells. Sequence analysis of unselected VDJ repertoire from T cells also revealed important consequences for B cell lymphogenesis and selection of B cell repertoire. As far as we know, this is the first evidence that some species completely rearrange VDJ genes in T cells. Our results also support the finding that B cells actively develop in the thymus.