Simcik W, Sheu T L, LeGrue S J
Department of Immunology, University of Texas M.D. Anderson Cancer Center, Houston 77030.
Cancer Immunol Immunother. 1989;30(4):219-26. doi: 10.1007/BF01665008.
The purpose of this study was to characterize the lymphocyte populations responsible for rejection of immunogenic (Imm+) tumor variants, and the cross-protective immunity engendered by Imm+ variants against the weakly immunogenic parental tumor. Immunogenic clones of the weakly immunogenic methylcholanthrene-induced fibrosarcoma MCA-F have been generated using 1-methyl-3-nitro-1-nitrosoguanidine, 5-aza-2'-deoxycytidine, or ultraviolet radiation (UV-B; 280-320 nm). These clones grow progressively in immunosuppressed adult-thymectomized irradiated mice, but are rejected by immunocompetent syngeneic hosts. The parental MCA-F tumor grows progressively in both groups. Mice that have rejected a challenge of 1 x 10(5) Imm+ cells show an anamnestic immune response against both the Imm+ clone and the parental MCA-F tumor. Using the local adoptive transfer assay and depletion of T-cell subsets with antibody plus complement, we show that immunity induced by the Imm+ variants against the parent MCA-F was mediated by the Thy1.2+, L3T4a+ population without an apparent contribution by Lyt2.1+ cells. Although antivariant immunity was also dependent upon Thy1.2+ cells, depletion of either the L3T4a+ or the Lyt2.1+ cells failed to abolish immunity against the variant. A role for Lyt2.1+ T lymphocytes in antivariant immunity, but not antiparent immunity, was supported by the results of cytotoxic T lymphocyte (CTL) assays. Following immunization with high numbers (1 x 10(5) to 5 x 10(5) of viable Imm+ cells, antivariant, but not antiparent CTL activity was detected in mixed lymphocyte tumor cell cultures. Immunization with lower numbers (3 x 10(4] of viable Imm+ or with high numbers of mitomycin-C-treated Imm+ engenders only antivariant immunity without parental cross-protection. Under these conditions lymphocytes mediating immunity against the variant in the local adoptive transfer assay were exclusively of the Thy1.2+, L3T4a+ phenotype, with no contribution from the Lyt2.1+ cells. Identical results were obtained for Imm+ clones of MCA-F induced by methylnitronitrosoguanidine, 5-azadeoxycytidine, and UV-B, suggesting that the nature of the antitumor immunity engendered by Imm+ is not significantly affected by the agent used. Furthermore, these results demonstrate that the cross-reactivity and cellular effectors of antitumor immunity in this system are influenced by the immunizing dose of Imm+ cells: the predominant effectors of both antivariant and parental-cross-reactive immunity were of the CD4+ T cell subclass, with a CD8+ cytotoxic population contributing to antivariant immunity only after high-dose immunization.
本研究的目的是鉴定负责免疫原性（Imm+）肿瘤变体排斥反应的淋巴细胞群体，以及Imm+变体对弱免疫原性亲本肿瘤产生的交叉保护性免疫。使用1-甲基-3-硝基-1-亚硝基胍、5-氮杂-2'-脱氧胞苷或紫外线辐射（UV-B；280 - 320 nm）已产生了弱免疫原性甲基胆蒽诱导的纤维肉瘤MCA-F的免疫原性克隆。这些克隆在免疫抑制的成年去胸腺照射小鼠中逐渐生长，但被免疫活性同基因宿主排斥。亲本MCA-F肿瘤在两组中均逐渐生长。已排斥1×10⁵个Imm+细胞攻击的小鼠对Imm+克隆和亲本MCA-F肿瘤均表现出回忆性免疫反应。使用局部过继转移试验以及用抗体加补体清除T细胞亚群，我们发现Imm+变体诱导的针对亲本MCA-F的免疫由Thy1.2⁺、L3T4a⁺群体介导，Lyt2.1⁺细胞无明显贡献。尽管抗变体免疫也依赖于Thy1.2⁺细胞，但清除L3T4a⁺或Lyt2.1⁺细胞均未能消除针对变体的免疫。细胞毒性T淋巴细胞（CTL）试验结果支持Lyt2.1⁺T淋巴细胞在抗变体免疫而非抗亲本免疫中起作用。用大量（1×10⁵至5×10⁵）活的Imm+细胞免疫后，在混合淋巴细胞肿瘤细胞培养物中检测到抗变体而非抗亲本的CTL活性。用少量（3×10⁴）活的Imm+细胞或大量丝裂霉素-C处理的Imm+细胞免疫仅产生抗变体免疫而无亲本交叉保护。在这些条件下，局部过继转移试验中介导针对变体免疫的淋巴细胞仅为Thy1.2⁺、L3T4a⁺表型，Lyt2.1⁺细胞无贡献。由甲基硝基亚硝基胍、5-氮杂脱氧胞苷和UV-B诱导的MCA-F的Imm+克隆获得了相同结果，表明Imm+产生的抗肿瘤免疫的性质不受所用试剂的显著影响。此外，这些结果表明该系统中抗肿瘤免疫的交叉反应性和细胞效应器受Imm+细胞免疫剂量的影响：抗变体和亲本交叉反应性免疫的主要效应器均为CD4⁺T细胞亚类，只有在高剂量免疫后CD8⁺细胞毒性群体才对抗变体免疫有贡献。
