Developmental heterogeneity of Vγ1.1 T cells in the mouse liver

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Abstract
Modifications at V–(D)–J junctions increase the diversity of T‐cell receptors (TCR). It has been shown that the levels of N‐nucleotide insertion at the V–(D)–J junction in TCR transcripts are different between fetal and adult stages. To clarify developmental stages and pathways of γδ T cells in the liver, we analysed the nucleotide sequence of Vγ1.1–Jγ4 junctions of intra‐hepatic lymphocytes (IHL), spleen cells and developing thymocytes from normal and athymic nude mice. The level of N‐insertion increased in thymocytes during ontogeny. The percentage of Vγ1.1–Jγ4 transcripts with N‐insertion was 3% at day 16 of gestation, 42% at newborn, and 89% at 7 weeks. Transcripts from normal IHL showed intermediate levels of N‐insertion between those of newborn and adult thymocytes. In contrast the percentage of N‐insertion in nude IHL was 47%, and this value was comparable to that of newborn thymocytes. Among the transcripts of normal IHL, the sequences common with nude IHL showed a newborn level of N‐insertion (38%), and the remaining sequences showed an adult level (89%). These results suggested the possibility that Vγ1.1‐expressing T cells in IHL might be a heterogeneous population consisting of the cells developed extrathymically as well as the cells developed intrathymically. The Vγ1.1–Jγ4 junctions from spleen cells showed less variability than those from IHL and adult thymocytes. It suggested that γδ T cells bearing specific Vγ1.1 TCR develop and/or home in the spleen.