Spellerberg M B, Zhu D, Thompsett A, King C A, Hamblin T J, Stevenson F K
Tenovus Laboratory, Southampton University Hospitals, United Kingdom.
J Immunol. 1997 Aug 15;159(4):1885-92.
Idiotypic determinants can act as tumor-associated Ags for B cell lymphoma. Vaccination with idiotypic protein and adjuvant is known to induce specific protection against lymphoma challenge in mice, largely mediated by anti-idiotypic Ab. For facilitating the approach for patients, the V(H) and V(L) genes used to encode the individual idiotypic determinants of each tumor can be obtained by PCR and assembled as single chain Fv (scFv). DNA vaccines containing scFv sequences alone induce low and poorly reproducible levels of anti-idiotypic Ab, likely to be insufficient to suppress tumor in patients. In addition, it may be necessary to break tolerance to Id in tumor bearers. By fusing the gene for fragment C of tetanus toxin to the C terminus of human scFv, we have promoted the anti-scFv Ab response in mice by >50-fold in three of three cases. The induced Abs are mainly against idiotypic determinants, and react specifically with patients' tumor cells, indicating optimal folding of the scFv molecule in the fusion protein. For both antigenic components of the DNA vaccine, the IgG subclass distribution showed a relative increase in IgG2a as compared with vaccination with IgM protein in adjuvant. In patients, the fusion gene should both promote anti-idiotypic Ab and induce Abs against fragment C of tetanus toxin. The latter response would provide a potentially useful comparative measure of the ability of patients to respond to conventional Ag delivered via DNA.
独特型决定簇可作为B细胞淋巴瘤的肿瘤相关抗原。已知用独特型蛋白和佐剂进行疫苗接种可诱导小鼠对淋巴瘤攻击产生特异性保护，这主要由抗独特型抗体介导。为便于应用于患者，用于编码每个肿瘤的各个独特型决定簇的V(H)和V(L)基因可通过聚合酶链反应（PCR）获得，并组装成单链Fv（scFv）。仅含scFv序列的DNA疫苗诱导的抗独特型抗体水平较低且重复性差，可能不足以抑制患者体内的肿瘤。此外，可能有必要打破肿瘤携带者对独特型的耐受性。通过将破伤风毒素C片段的基因与人scFv的C末端融合，我们在三例实验中有三例将小鼠体内的抗scFv抗体反应提高了50倍以上。诱导产生的抗体主要针对独特型决定簇，并能与患者的肿瘤细胞特异性反应，这表明融合蛋白中的scFv分子折叠良好。对于DNA疫苗的两种抗原成分，与用佐剂中的IgM蛋白进行疫苗接种相比，IgG亚类分布显示IgG2a相对增加。在患者中，融合基因应既能促进抗独特型抗体的产生，又能诱导产生针对破伤风毒素C片段的抗体。后一种反应将为患者对通过DNA递送的传统抗原的反应能力提供一个潜在有用的比较指标。
