Aldo-Benson M
Cell Immunol. 1986 Dec;103(2):417-25. doi: 10.1016/0008-8749(86)90101-2.
Membrane depolarization is one of the earliest events in activation of cells by ligand receptor interaction. It is known that crosslinking of antigen-specific Ig receptors on B cells by antigen can induce membrane depolarization and subsequent Ia antigen expression on the cell surface. To determine whether a tolerance-inducing form of the antigen can also induce membrane depolarization after Ig receptor binding we used splenic B cells enriched for dinitrophenyl (DNP)-specific cells and determined relative membrane potential in these cells after binding of DNP-murine IgG2a (MGG) (tolerogen) or antigens (DNP-keyhole limpet hemocyanin (KLH) and DNP-Ficoll). Relative membrane potential was determined by loading the cells with the dye, 3.3-dipentyloxacarboxyanine (DiOC5(3)) after 2 hr incubation with ligand and determining relative fluorescence intensity on the fluorescence-activated cell sorter (FACS). Carriers alone did not depolarize these normal cell populations, but 100% of DNP-specific cells were depolarized by DNP-KLH and DNP-MGG while 85% were depolarized by DNP-Ficoll. To determine if tolerant B cells could be depolarized by antigen we induced tolerance in vitro or in vivo with DNP-MGG and measured the depolarization of DNP-specific B cells in response to antigens and tolerogen. DNP-specific B cells made tolerant by DNP-MGG underwent membrane depolarization when incubated with either DNP-KLH, DNP-MGG, or DNP-Ficoll but not with carriers alone. These data suggest that tolerogen induces membrane depolarization equally as well as antigen in normal cells. In addition, tolerant cells can be depolarized by Ig receptor crosslinking with either antigen or tolerogen. Thus, tolerance does not block the early membrane events induced by antigen in B cells.
膜去极化是配体-受体相互作用激活细胞过程中最早发生的事件之一。已知抗原使B细胞上抗原特异性Ig受体交联可诱导膜去极化以及随后细胞表面Ia抗原的表达。为了确定抗原的耐受诱导形式在Ig受体结合后是否也能诱导膜去极化，我们使用富集二硝基苯基（DNP）特异性细胞的脾B细胞，并在结合DNP-小鼠IgG2a（MGG）（耐受原）或抗原（DNP-钥孔戚血蓝蛋白（KLH）和DNP-菲可）后测定这些细胞的相对膜电位。在与配体孵育2小时后，通过用染料3,3-二戊基氧杂羰花青（DiOC5(3)）加载细胞并在荧光激活细胞分选仪（FACS）上测定相对荧光强度来确定相对膜电位。单独的载体不会使这些正常细胞群体去极化，但100%的DNP特异性细胞被DNP-KLH和DNP-MGG去极化，而85%被DNP-菲可去极化。为了确定耐受的B细胞是否能被抗原去极化，我们用DNP-MGG在体外或体内诱导耐受，并测量DNP特异性B细胞对抗原和耐受原的去极化反应。用DNP-MGG诱导产生耐受的DNP特异性B细胞在与DNP-KLH、DNP-MGG或DNP-菲可孵育时会发生膜去极化，但与单独的载体孵育时则不会。这些数据表明，耐受原在正常细胞中诱导膜去极化的能力与抗原相当。此外，耐受细胞可通过与抗原或耐受原交联Ig受体而被去极化。因此耐受性不会阻断抗原在B细胞中诱导的早期膜事件。
