| Abstract: |
Two types of T lymphocytes can be generated intrathymically, distinguishable by either TCR-γδ or -αβ surface expression. Regulation of the intrathymic divergence of these cells is unresolved, at least in part because thymically derived γδ cells have rarely been studied. We used quantitative Southern blotting together with PCR-based cloning/sequencing and restriction fragment length polymorphism to analyze TCR-α and -β gene recombination in thymically derived γδ cells. We found that TCR-β gene recombination is a frequent occurrence in thymic γδ cells. Furthermore, not only do complete (V-D-J) TCR-β gene rearrangements occur in thymic γδ cells, but the frequency of in-frame rearrangements is greater than would be predicted based upon random occurrence. In contrast, we show that thymically derived γδ cells do not make detectable rearrangements of the TCR-α locus. These studies clearly demarcate a point for αβ vs γδ commitment in the thymus, after TCR-β but before TCR-α gene recombination. Further, while our data support γδ lineage commitment as a consequence of successful TCR-γ and -δ gene rearrangement, we do not find support for a competitive model of lineage commitment, since productive TCR-β gene rearrangement does not necessarily relegate cells to the αβ lineage. |
| Keywords: |
genetics; molecular genetics; t lymphocyte; t-lymphocytes; mouse; animal; animals; mice; cell differentiation; mice, inbred c57bl; c57bl mouse; biosynthesis; immunology; lymphocyte activation; gene rearrangement; molecular sequence data; nucleotide sequence; base sequence; lymphocyte antigen receptor; receptors, antigen, t-cell, alpha-beta; gene rearrangement, t-lymphocyte; southern blotting; open reading frame; receptors, antigen, t-cell, gamma-delta; open reading frames; blotting, southern; article
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