Szabo G, Pine P S, Weaver J L, Rao P E, Aszalos A
Department of Biophysics, University Medical School of Debrecen, Hungary.
Immunol Cell Biol. 1994 Aug;72(4):319-25. doi: 10.1038/icb.1994.48.
Several accessory molecules were shown to play important roles in T cell functions and be in close proximity to the T cell receptor (TcR/CD3). The L-selectin molecule (Leu8, LAM1-1, LECAM1) also plays an important role in lymphocyte homing and proliferation. We were interested in determining the proximity of this molecule to the TcR/CD3 complex on live peripheral human T cells. Using a fluorescence energy transfer method, designed to study individual cells, we could show that L-selectin is within 170 A of the TcR/CD3 complex. Monoclonal antibody directed against the LAM1-1 (Leu8) epitope of the L-selectin molecule suppressed the mitogenic activity of antibodies specific for various CD3 epitopes in vitro. Intracellular Ca2+ mobilization obtained with wt31 followed by cross-linking antibody or with anti-CD3 was not influenced by anti-Leu8 antibody. Also antibody directed against the LAM1-1 epitope did not influence the binding of the mitogenic antibodies, as shown by fluorescence-based flow cytometry. Therefore, we suggest that binding of TcR/CD3 bound mitogenic antibodies to accessory cell Fc receptors may be hindered by antibodies bound to the close proximity L-selectin molecules.
几种辅助分子被证明在T细胞功能中发挥重要作用，并且与T细胞受体（TcR/CD3）紧密相邻。L-选择素分子（Leu8、LAM1-1、LECAM1）在淋巴细胞归巢和增殖中也起着重要作用。我们感兴趣的是确定该分子在活体人外周T细胞上与TcR/CD3复合物的接近程度。使用一种旨在研究单个细胞的荧光能量转移方法，我们能够证明L-选择素在距离TcR/CD3复合物170埃以内。针对L-选择素分子的LAM1-1（Leu8）表位的单克隆抗体在体外抑制了针对各种CD3表位的抗体的促有丝分裂活性。用wt31随后交联抗体或抗CD3获得的细胞内Ca2+动员不受抗Leu8抗体的影响。如基于荧光的流式细胞术所示，针对LAM1-1表位的抗体也不影响促有丝分裂抗体的结合。因此，我们认为与TcR/CD3结合的促有丝分裂抗体与辅助细胞Fc受体的结合可能会被与紧密相邻的L-选择素分子结合的抗体所阻碍。
