Antigen Triggering Selectively Increases TCRBV Gene Transcription

Abstract

When the TCR binds Ag it is phosphorylated, internalized, and degraded. We wished to examine whether this process was accompanied by a specific concomitant increase in TCR mRNA levels. To do this, PBMC and a T cell clone were cultured with a series of superantigens and an alloantigen. Only T cells specifically responding to an antigenic stimulus had increased levels of TCR β-chain variable (TCRBV)-specific mRNA. This response was apparent after 48 h, peaked around 72 h, and was still elevated after 7 days. Increased gene transcription appeared to be driven solely by Ag as specific Ag depletion prevented culture supernatants transferring this effect. The level of TCRBV mRNA elevation was not influenced by the stimulating Ag, but appeared dependent on the gene encoding the stimulated TCR. Reporter gene assays, using cloned TCRBV gene promoters, confirmed both that TCR gene transcription rises after stimulation and that basal and stimulated levels of TCR transcription vary between different TCRBV genes. These data conclusively demonstrate that there is no direct relationship between TCRBV mRNA and T cell number, and that future repertoire studies must take both factors into account.

Characterization of antigen‐specific repertoire diversity following in vitro restimulation by a recombinant adenovirus expressing human cytomegalovirus pp65

“…Immunoscope analysis revealed that most TCRBV found before in vitro restimulation were conserved after in vitro restimulation but also that diversity in terms of TCRBV usage was increased, consistent with the observation that antigen triggering selectively increases TCRBV gene transcription [31]. Besides the number of cells used before and after in vitro restimulation, the difference in RNA extraction yield and in cDNA synthesis could be explained the augmentation of transcripts after in vitro restimulation.…”

Different Qualitative and Quantitative Regulation of Vβ TCR Transcripts During Early Acute Allograft Rejection and Tolerance Induction

“…These different patterns could have been shaped by thymus selection processes as well as by subtle preimmune constraints in the TCR repertoire (24). Interestingly, whereas T cell activation is characterized by a down-regulation of membranous TCR (25), TCR chain mRNA accumulation is observed (9,26,27). However, V␤ transcript accumulation is the result of a composite regulation depending on both activation (26) and kinetics of T cells infiltrating the graft.…”

“…Interestingly, whereas T cell activation is characterized by a down-regulation of membranous TCR (25), TCR chain mRNA accumulation is observed (9,26,27). However, V␤ transcript accumulation is the result of a composite regulation depending on both activation (26) and kinetics of T cells infiltrating the graft. In the model used in this paper, the infiltrate is maximum on day 5 during rejection and tolerance induction following DST priming (22,28), and T cells are found at similar levels in rejected and tolerated grafts (22, 28, FIGURE 3.…”

Direct Recognition of Foreign MHC Determinants by Naive T Cells Mobilizes Specific Vβ Families Without Skewing of the Complementarity-Determining Region 3 Length Distribution

“…For example, polyclonal expansions of specific V␤ families would not be detected by these methods. To overcome this limitation, we took advantage of the transcriptional activation of the TCR ␤-chain in activated T cells (34,35). For each V␤ family, mRNA accumulation was quantified by real-time RT-PCR, and these values were displayed according to the distribution of CDR3 lengths, as determined by the Immunoscope method (31).…”