Mackay C R, Hein W R, Brown M H, Matzinger P
Basel Institute for Immunology, Switzerland.
Eur J Immunol. 1988 Nov;18(11):1681-8. doi: 10.1002/eji.1830181105.
The CD2 adhesion/activation molecule on the surface of mammalian T lymphocytes binds to a ubiquitous receptor, LFA-3. We show that CD2 in sheep differs significantly in its expression from CD2 in humans, and this most likely relates to the high level of expression of the sheep LFA-3 molecule. In sheep, in contrast to man, CD2 was weakly expressed on peripheral T cells and thymocytes. Moreover, a large subset of T cells identified by the monoclonal antibody T19 and considered to be gamma/delta receptor-bearing T cells completely lacked the CD2 molecule. T19+ cells constituted up to 50% of peripheral blood T cells in lambs, and 20-30% of T cells in older sheep, whereas the CD4+ and CD8+ subsets, which are both CD2+, constituted relatively small subsets in peripheral blood. Only those T cells which did express CD2 adhered as "rosettes" to dendritic cells, and the localization of CD2 to the membrane junction indicated that CD2 was critical for this adhesion. However, CD2 adhesion was not necessary for CTL-mediated killing of allogeneic target cells, since T19+ cells generated in bulk mixed lymphocyte culture were extremely efficient at killing appropriate target cells. Some of the behavioral differences between T19+ and CD4+/CD8+ subsets might be explained by the presence or absence of CD2. The results also indicate that the expression of CD2 (and LFA-3) may differ markedly between species.
哺乳动物T淋巴细胞表面的CD2黏附/激活分子与一种普遍存在的受体LFA-3结合。我们发现，绵羊的CD2在表达上与人类的CD2有显著差异，这很可能与绵羊LFA-3分子的高表达水平有关。与人类不同，在绵羊中，CD2在外周血T细胞和胸腺细胞上的表达较弱。此外，被单克隆抗体T19识别并被认为是携带γ/δ受体的T细胞的一个大子集完全缺乏CD2分子。T19+细胞在羔羊外周血T细胞中占比高达50%，在成年绵羊的T细胞中占20%-30%，而同为CD2+的CD4+和CD8+亚群在外周血中所占比例相对较小。只有那些表达CD2的T细胞以“玫瑰花结”的形式黏附于树突状细胞，并且CD2在膜连接处的定位表明CD2对这种黏附至关重要。然而，CD2黏附对于CTL介导的同种异体靶细胞杀伤并非必需，因为在大量混合淋巴细胞培养中产生的T19+细胞在杀伤合适靶细胞方面极其高效。T19+和CD4+/CD8+亚群之间的一些行为差异可能可以用CD2的有无来解释。结果还表明，CD2（和LFA-3）的表达在不同物种之间可能存在显著差异。
