Schott M E, Wells D T, Schlom J, Abrams S I
Laboratory of Tumor Immunology and Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Cell Immunol. 1996 Dec 15;174(2):199-209. doi: 10.1006/cimm.1996.0310.
The utility of multiple antigenic peptides (MAPs) for the induction of antibody and cellular immune responses in animal models has been demonstrated for a variety of peptide epitopes involved in human disease. However, little is known about immune responses to MAPs constructed with antigenic tumor epitopes, nor has peptide specificity in branched forms been addressed. A potentially important advantage of the MAP system over linear peptide immunogens for clinical applications is elimination of the need for a protein carrier with its associated toxicity and immunogenicity. Here, we examined cellular immune responses following in vivo administration of MAPs incorporating a 13-mer T helper epitope from point-mutated ras p21 (ras V12) and compared the potency of the responses to that of the linear peptide. The Gly --> Val mutation in position 12, which is associated with a range of human carcinomas, represents a useful system for evaluating the specificity of the immune response. In initial studies with the point-mutated linear peptide epitope, optimal in vitro proliferation responses were obtained following sc administration of the peptide in a squalane-containing adjuvant formulation. Comparative immunization studies using point-mutated MAPs bearing two, four, or eight branches were administered either in saline or in adjuvant. These studies showed that adjuvant was required for the induction of cellular immune responses using both linear and all three forms of branched peptides. Moreover, there was no apparent advantage of using any of the MAPs vs linear peptide when equivalent mass amounts were administered, i.e., the intensity of the immune response was no greater using any of the branched structures compared to the linear form. Specificity of the in vivo responses for both the linear and the MAP immunogens was demonstrated by the higher stimulation indices observed in vitro in the presence of the mutant ras V12 vs the normal ras G12 linear peptide. No apparent cellular immune response to the MAP core structure itself was observed. However, a nonspecific response to the two-branched MAP2G12 structure was observed in some assays, the nature of which is unknown at this time. This work represents the first reported investigation of a cellular immune response using MAP immunogens incorporating a tumor-specific peptide epitope and demonstrates that linear peptides are as efficient as three different MAP structures in the generation of specific T cell responses.
多种抗原肽（MAPs）在动物模型中诱导抗体和细胞免疫反应的效用已在多种涉及人类疾病的肽表位中得到证实。然而，对于由抗原性肿瘤表位构建的MAPs的免疫反应知之甚少，分支形式的肽特异性也未得到探讨。与线性肽免疫原相比，MAP系统在临床应用中的一个潜在重要优势是无需蛋白质载体及其相关的毒性和免疫原性。在此，我们检测了体内给予包含来自点突变ras p21（ras V12）的13聚体T辅助表位的MAPs后的细胞免疫反应，并将反应效力与线性肽的效力进行了比较。第12位的甘氨酸→缬氨酸突变与一系列人类癌症相关，是评估免疫反应特异性的有用系统。在对点突变线性肽表位的初步研究中，在含角鲨烷的佐剂制剂中皮下注射该肽后，获得了最佳的体外增殖反应。使用带有两个、四个或八个分支的点突变MAPs进行的比较免疫研究，分别在生理盐水或佐剂中进行。这些研究表明，使用线性肽和所有三种形式的分支肽诱导细胞免疫反应都需要佐剂。此外，当给予等量质量时，使用任何一种MAPs与线性肽相比都没有明显优势，即与线性形式相比，任何一种分支结构的免疫反应强度都没有更大。通过在体外存在突变型ras V12与正常ras G12线性肽时观察到的较高刺激指数，证明了线性和MAP免疫原在体内反应的特异性。未观察到对MAP核心结构本身的明显细胞免疫反应。然而，在一些试验中观察到对双分支MAP2G12结构的非特异性反应，其性质目前尚不清楚。这项工作是首次报道的使用包含肿瘤特异性肽表位的MAP免疫原进行细胞免疫反应的研究，并证明线性肽在产生特异性T细胞反应方面与三种不同的MAP结构一样有效。
