Expression of T-Cell Receptor β-Chain mRNA and Proteininγ/δT-Cells from Euthymic and Athymic Rats:Implications for T-Cell Lineage Divergence

摘要

The relationship betweenα/βandγ/δT-cell lineages was studied in rats using RT-PCR analysisof TCRβ transcripts inγ/δT-cell hybridomas and an intracellular staining technique todetect TCRβ protein in primaryγ/δT-cells. We report the presence of functional TCRβ transcriptsin 2/9γ/δT-cell hybridomas. About 15 % of peripheralγ/δT-cells and thymocytes alsoexpress TCRβ protein, giving a minimum estimate for successful Tcrb rearrangement basedonexvivosingle cell analysis. In athymic rats,γ/δT-cells expressing intracellular β proteinare present but at a lower frequency than in euthymic controls, suggesting that in the thymus,moreγ/δT-cell precursors pass through a stage where functional β rearrangement hasoccurred than in extrathymic sites. Analysis of TCR expression in purified transitory immatureCD4-8+(iCD8SP) thymocytes and their spontaneously developing CD4+8+(DP) progenyshowed that TCRγmRNA is expressed in iCD8SP cells but not in their immediate DPprogeny that reinitiate RAG-1 transcription and commenceα/βTCR expression. We concludethat ratγ/δT cells can separate from theα/βlineage after TCRβ expression, but not afterentry into the DP compartment.