T-cell receptor (TCR) usage in Lewis rat experimental autoimmune encephalomyelitis: TCR beta-chain-variable-region V beta 8.2-positive T cells are not essential for induction and course of disease.

Predominant usage of V beta 8.2 gene segments, encoding a T-cell receptor (TCR) beta chain variable region, has been reported for pathogenic Lewis rat T cells reactive to myelin basic protein (MBP). However, up to 75% of the alpha/beta T cells in a panel of MBP-specific T-cell lines did not display TCR V beta 8.2, V beta 8.5, V beta 10, or V beta 16 elements. To further investigate TCR usage, we sorted the T-cell lines for V beta 8.2- and V beta 10-positive T cells or depleted the lines of cells with these TCRs. V beta 8.2-positive T cells and one of the depleted T-cell lines strongly reacted against the MBP peptide MBP-(68-88). The depleted T-cell line caused marked experimental autoimmune encephalomyelitis (EAE) even in Lewis rats in which endogenous V beta 8.2-positive T cells had been eliminated by neonatal treatment with anti-V beta 8.2 monoclonal antibodies. T-cell hybridomas generated from this line predominantly used V beta 3 TCR genes coexpressed with TCR V alpha 2 transcripts, which were also used by V beta 8.2-positive T cells. Furthermore, V beta 10-positive T cells reactive to MBP-(44-67) were encephalitogenic when injected immediately after positive selection. After induction of EAE by sorted V beta 8.2- or V beta 10-positive T-cell lines, immunocytochemical analysis of the spinal cord tissue showed a predominance of the injected TCR or of nontypable alpha/beta T cells after injection of the depleted line. Our results demonstrate heterogeneity of TCR beta-chain usage even for a single autoantigen in an inbred strain. Moreover, V beta 8.2-positive T cells are not essential for the induction and progression of adoptive-transfer EAE. IMAGES:

已有研究表明，针对髓鞘碱性蛋白（myelin basic protein，MBP）的致病性Lewis大鼠T细胞，会优先使用编码T细胞受体（T-cell receptor，TCR）β链可变区的Vβ8.2基因片段。然而，在一组MBP特异性T细胞系中，多达75%的αβ T细胞并不表达TCR Vβ8.2、Vβ8.5、Vβ10或Vβ16基因片段。为进一步探究TCR的使用偏好，本研究通过细胞分选获取Vβ8.2阳性与Vβ10阳性T细胞，或通过细胞耗竭处理移除细胞系中携带此类TCR的细胞。Vβ8.2阳性T细胞以及其中一株经耗竭处理的细胞系，均可强烈响应MBP肽段MBP-(68-88)。即便在内源性Vβ8.2阳性T细胞已通过新生期注射抗Vβ8.2单克隆抗体被清除的Lewis大鼠体内，该经耗竭处理的细胞系仍可诱发显著的实验性自身免疫性脑脊髓炎（experimental autoimmune encephalomyelitis，EAE）。从该细胞系构建的T细胞杂交瘤，主要使用与TCR Vα2转录本共表达的Vβ3 TCR基因，而Vβ8.2阳性T细胞同样会使用此类转录本。此外，针对MBP-(44-67)的Vβ10阳性T细胞在阳性分选后即刻注射时，可表现出致脑炎活性。在通过分选获得的Vβ8.2阳性或Vβ10阳性T细胞系诱发EAE后，对脊髓组织进行免疫细胞化学分析，结果显示注射的TCR占主导；而在注射经耗竭处理的细胞系后，脊髓组织中则以无法分型的αβ T细胞为主。本研究结果表明，即便在近交系动物中，针对单一自身抗原的T细胞，其TCRβ链的使用模式仍存在异质性。此外，Vβ8.2阳性T细胞并非过继转移EAE的诱导与进展所必需的细胞群体。图像：