Aszalos A, Pine P S, Weaver J L, Rao P E
Center for Drug Evaluations and Research, FDA, Washington, DC 20204.
Cell Immunol. 1994 Aug;157(1):81-91. doi: 10.1006/cimm.1994.1207.
It has previously been shown that crosslinking of the CD4 molecule, either with anti-Leu3a mAb or with gp120 (the HIV coat protein) plus anti-gp120 mAb, suppresses activation induced by wt31, a TcR/CD3-specific mAb. This suppression was associated with hindrance of the necessary association of the p56lck kinase bearing CD4 molecule with the TcR/CD3 complex. In this paper we demonstrate that this crosslinking-induced suppression can be bypassed by perturbing the microfilament system of CD4+ cells by pretreatment with 1 microM cytochalasin D. Using the fluorescence resonance energy transfer method, we have shown that the cytochalasin D-affected increase of mitogenesis is not due to changes in the TcR/CD3 to CD4 distance. Likewise, other membrane biophysical parameters, membrane potential and lateral diffusion of surface receptors, cannot be associated with these cytochalasin D-affected mitogenic changes. Cytochalasin D treatment elevates intracellular Ca2+ levels induced by wt31 mAb plus crosslinking and generates a TcR/CD3-dependent signal which is cyclosporin sensitive.
先前已经表明，用抗Leu3a单克隆抗体或用gp120（HIV外壳蛋白）加抗gp120单克隆抗体使CD4分子交联，可抑制由wt31（一种TcR/CD3特异性单克隆抗体）诱导的激活。这种抑制与携带CD4分子的p56lck激酶与TcR/CD3复合物的必要结合受阻有关。在本文中，我们证明，通过用1微摩尔细胞松弛素D预处理来扰乱CD4+细胞的微丝系统，可以绕过这种交联诱导的抑制。使用荧光共振能量转移方法，我们已经表明，细胞松弛素D影响的有丝分裂增加不是由于TcR/CD3与CD4距离的变化。同样，其他膜生物物理参数，膜电位和表面受体的横向扩散，也与这些细胞松弛素D影响的有丝分裂变化无关。细胞松弛素D处理提高了由wt31单克隆抗体加交联诱导的细胞内Ca2+水平，并产生了对环孢素敏感的TcR/CD3依赖性信号。
