O'Keeffe M A, Metcalfe S A, Cunningham C P, Walker I D
Department of Veterinary Science, The University of Melbourne, Cnr Park Dve and Flemington Rd, Parkville, VIC 3052, Australia.
Immunogenetics. 1999 Jan;49(1):45-55. doi: 10.1007/s002510050462.
The sheep T19 multigene family contains at least 50 genes which are thought to be expressed exclusively on gammadelta T cells. The archetypal T19 molecule (represented by a full-length cattle cDNA clone termed WC1) is thought to have a relative molecular mass of about 220 000 and to contain 11 scavenger receptor cysteine rich (SRCR) repeats and a long cytoplasmic tail. In this study, purified CD4(+) and gammadeltaTCR+ sheep lymphocytes were examined by reverse transcriptase-polymerase chain reaction for the expression of T19 molecules. As expected, gammadelta T cells were found to express T19 molecules which closely resembled the archetypal form. However, CD4(+) alphabeta T cells were found to express at least two different types of T19 molecules; one resembled the previously described T19 molecules of gammadelta T cells which possessed the archetypal WC1-like structure, but a novel type of T19 variant which lacked SRCR domains 10 and 11 was also found in CD4(+) T cells but not gammadelta T cells. This novel molecule exhibited an unusual, incomplete SRCR repeat 9 joined directly to a hinge region. The transmembrane and cytoplasmic domains of this unusual T19 variant resembled the cattle T19 clone WC1, except that a complete exon within the cytoplasmic region was missing. These results, in contradistinction to existing serological data, suggest that expression of the T19 gene family is not confined to gammadelta T cells. Selected T19 genes are apparently expressed within CD4(+) T cells and possibly other lymphocytes as well.
绵羊T19多基因家族包含至少50个基因，这些基因被认为仅在γδT细胞上表达。典型的T19分子（由一个称为WC1的全长牛cDNA克隆代表）被认为相对分子质量约为220 000，含有11个富含半胱氨酸的清道夫受体（SRCR）重复序列和一条长的胞质尾巴。在本研究中，通过逆转录聚合酶链反应检测纯化的CD4(+)和γδTCR+绵羊淋巴细胞中T19分子的表达。正如预期的那样，发现γδT细胞表达与典型形式非常相似的T19分子。然而，发现CD4(+)αβT细胞表达至少两种不同类型的T19分子；一种类似于先前描述的具有典型WC1样结构的γδT细胞的T19分子，但在CD4(+)T细胞而非γδT细胞中也发现了一种新型的T19变体，其缺少SRCR结构域10和11。这种新型分子表现出一个不寻常的、不完整的SRCR重复序列9直接连接到一个铰链区。这种不寻常的T19变体的跨膜和胞质结构域类似于牛T19克隆WC1，只是胞质区域内一个完整的外显子缺失。这些结果与现有的血清学数据相反，表明T19基因家族的表达并不局限于γδT细胞。选定的T19基因显然在CD4(+)T细胞以及可能的其他淋巴细胞中表达。
