Heaton K M, Ju G, Grimm E A
Department of Tumor Biology, University of Texas M. D. Anderson Cancer Center, Houston 77030.
Cancer Res. 1993 Jun 1;53(11):2597-602.
Cancer patients undergoing interleukin (IL)-2-based immunotherapy frequently experience dose-limiting side effects believed to be caused by the actions of such cytokines as IL-1 beta, tumor necrosis factor (TNF)-alpha and -beta, and interferon-gamma (IFN-gamma). Human peripheral blood mononuclear cells (PBMC) or monocyte-depleted peripheral blood lymphocytes were stimulated for up to 7 days by either of 2 IL-2 analogues (R38A or F42K) that bind to the intermediate-affinity IL-2 beta gamma receptor but have reduced abilities to bind the high-affinity IL-2 receptor. We previously reported that these IL-2 analogues retain the ability to generate lymphokine-activated killing by PBMC. In this study, we analyzed the cytokine content of supernatants from stimulated PBMC and peripheral blood lymphocyte cultures by enzyme-linked immunosorbent assay. The secretions of IL-1 beta, TNF-alpha, and -beta, and IFN-gamma induced by either R38A or F42K were markedly reduced compared with secretions produced in response to recombinant wild-type IL-2. In 4 experiments, secretion was reduced an average of 39% for IL-1 beta, 57% for TNF-alpha, 83% for TNF-beta, and 86% for IFN-gamma. Polymerase chain reaction analysis of recombinant wild-type IL-2 or analogue-stimulated PBMC did not reveal the presence of IL-2 mRNA; thus, differential production of endogenous IL-2 could not account for these findings. These data suggest the interaction of IL-2 and the high-affinity IL-2 receptor on human PBMC or peripheral blood lymphocyte is required for maximal secretion of IL-1 beta, TNF-alpha, TNF-beta, and IFN-gamma. Because such cytokines are believed to mediate the toxicity seen with IL-2-based immunotherapies, IL-2 analogues with reduced binding to the high affinity IL-2 receptor may prove to be an effective and less toxic means of cancer treatment.
接受基于白细胞介素（IL）-2的免疫疗法的癌症患者经常会出现剂量限制性副作用，据信这些副作用是由IL-1β、肿瘤坏死因子（TNF）-α和-β以及干扰素-γ（IFN-γ）等细胞因子的作用引起的。用两种与中等亲和力的IL-2βγ受体结合但与高亲和力IL-2受体结合能力降低的IL-2类似物（R38A或F42K）刺激人外周血单核细胞（PBMC）或去除单核细胞的外周血淋巴细胞长达7天。我们之前报道过，这些IL-2类似物保留了通过PBMC产生淋巴因子激活杀伤作用的能力。在本研究中，我们通过酶联免疫吸附测定法分析了刺激后的PBMC和外周血淋巴细胞培养上清液中的细胞因子含量。与重组野生型IL-2刺激产生的分泌相比，R38A或F42K诱导的IL-1β、TNF-α和-β以及IFN-γ的分泌明显减少。在4个实验中，IL-1β的分泌平均减少39%，TNF-α减少57%，TNF-β减少83%，IFN-γ减少86%。对重组野生型IL-2或类似物刺激的PBMC进行聚合酶链反应分析未发现IL-2 mRNA的存在；因此，内源性IL-2的差异产生不能解释这些发现。这些数据表明，IL-2与人PBMC或外周血淋巴细胞上的高亲和力IL-2受体相互作用是IL-1β、TNF-α、TNF-β和IFN-γ最大分泌所必需的。因为据信这些细胞因子介导基于IL-2的免疫疗法中出现的毒性，与高亲和力IL-2受体结合减少的IL-2类似物可能被证明是一种有效且毒性较小的癌症治疗手段。
