Keren Z, Berke G
Cell Immunol. 1984 Dec;89(2):458-77. doi: 10.1016/0008-8749(84)90347-2.
The exquisite immunological specificity of cytotoxic T lymphocytes-target cell (CTL-TC) conjugation and lysis is overridden in the presence of certain plant lectins. The role of concanavalin A (Con A) in lectin-dependent, CTL-mediated cytolysis (LDCC) has been investigated. Papain-treated TC are refractory to LDCC, but regain susceptibility following a 3-hr incubation without the enzyme. Papain-treated TC allowed to recover in the presence of tunicamycin (TM; an inhibitor of N-linked glycosylation), are totally refractory to LDCC. Refractoriness of TM-treated TC to LDCC is not due to an overall resistance to lysis or to lack of Con A binding, as these cells can be lysed by specifically sensitized CTL or by H-2 antibody and complement and display a sufficiently high Con A-binding capacity, indistinguishable from intact TC, probably through O-linked, cell-surface glycosyl residues. The finding that TC (TM-treated) capable of binding normal Con A quantities cannot, however, engage in lectin-dependent CTL-TC conjugation and lysis indicates that Con A must react selectively with a specific TC-surface component(s), thereby rendering the TC recognizable by effector CTL, rather than by simply bridging ("glueing") CTL and TC. Affinity absorption and elution from Sepharose-Con A beads as well as specific immunoprecipitations by antibodies against cell surface determinants, have shown effective Con A binding to TC surface components of molecular weights corresponding to 45-kDa product of the H-2K and D MHC genes and, possibly, to a 30-kDa component. Antibodies against MHC proteins but not against non-MHC surface proteins of the TC have produced effective inhibition of LDCC. This and previous investigations show that in nonspecific LDCC as in specific CTL-mediated lysis, TC-MHC determinants are involved in signaling TC recognition and lysis.
在某些植物凝集素存在的情况下，细胞毒性T淋巴细胞与靶细胞（CTL-TC）结合及裂解所具有的精确免疫特异性会被破坏。已对伴刀豆球蛋白A（Con A）在凝集素依赖性、CTL介导的细胞溶解（LDCC）中的作用进行了研究。用木瓜蛋白酶处理过的靶细胞对LDCC具有抗性，但在无该酶的情况下孵育3小时后恢复敏感性。在衣霉素（TM；N-连接糖基化的抑制剂）存在下恢复的经木瓜蛋白酶处理的靶细胞对LDCC完全具有抗性。TM处理的靶细胞对LDCC的抗性并非由于对裂解的全面抗性或缺乏Con A结合，因为这些细胞可被特异性致敏的CTL或H-2抗体及补体裂解，并显示出足够高的Con A结合能力，与完整靶细胞无异，可能是通过O-连接的细胞表面糖基残基。然而，能够结合正常量Con A的（经TM处理的）靶细胞却不能参与凝集素依赖性的CTL-TC结合及裂解，这一发现表明Con A必须与特定靶细胞表面成分选择性反应，从而使靶细胞能够被效应CTL识别，而不是简单地桥接（“黏合”）CTL和靶细胞。从琼脂糖-Con A珠上进行亲和吸附和洗脱以及通过针对细胞表面决定簇的抗体进行特异性免疫沉淀，已表明Con A能有效结合分子量相当于H-2K和D MHC基因45-kDa产物的靶细胞表面成分，可能还结合一种30-kDa成分。针对MHC蛋白而非靶细胞非MHC表面蛋白的抗体可有效抑制LDCC。这一研究以及先前的研究表明，在非特异性LDCC中，如同在特异性CTL介导的裂解中一样，靶细胞-MHC决定簇参与了靶细胞识别和裂解的信号传导。
