Miki S, Ksander B, Streilein J W
Department of Microbiology and Immunology, University of Miami Medical School, Fl 33101.
Reg Immunol. 1992 Nov-Dec;4(6):352-62.
DBA/2-derived P815 tumor cells form progressively growing tumors when injected into the anterior chamber (AC) of normal BALB/c eyes. By contrast, P815 cells injected into the subconjunctival (SCon) space of BALB/c mice are promptly rejected. Despite these very different outcomes, both AC and SCon tumors elicit an equal clonal expansion of tumor-specific precursor cytotoxic T cells (pTc) within the draining cervical lymph nodes. Moreover, tumor-specific pTc migrate systemically and infiltrate both AC and SCon tumor-containing eyes. The present study explores the hypothesis that pTc generated in response to AC P815 tumors are less efficient "killers" than their SCon counterparts. To address this issue pTc were restimulated in vitro in the presence of exogenous lymphokines to initiate the terminal differentiation of pTc into fully functional cytotoxic T cells (Tc). Then an assay was developed to evaluate the capacity of AC and SCon CD8+ Tc to eliminate P815 tumor cells growing in vitro, i.e., achieve a "cure." This assay established the day tumor cells were completely eliminated (cure), as well as the rate of tumor cell removal. Using this approach it has been learned that pTc harvested from AC and SCon tumor-bearing mice have the same potential for eliminating P815 tumor cells in vitro. Moreover, the efficiency of achieving an in vitro tumor "cure" was found to be remarkably enhanced if exogenous lymphokines, as a surrogate source of T cell "help," were included in the cultures at the time effector lymphocytes were added to the proliferating tumor target cells. This latter finding emphasizes the need for sustained availability of helper factors in order to maximize the efficiency with which Tc can eliminate tumor cells. We interpret the results to mean that successful rejection of tumors in vivo is likely to turn upon (a) arrival of tumor-specific pTc at the tumor site, (b) delivery of "help" that promotes the terminal conversion of these cells into Tc, and (c) sustained presence of "help" which promotes the efficiency of immune elimination of tumor cells. Since equally large numbers of P815-specific pTc enter AC and SCon tumor sites in BALB/c mice, the failure of rejection in the former may be due to an inability of the host to provide immediate and sustained local T cell help. Implications of these studies for the development of immunotherapies for intraocular tumors are discussed.
将源自DBA/2的P815肿瘤细胞注入正常BALB/c小鼠的前房（AC）时，会形成逐渐生长的肿瘤。相比之下，注入BALB/c小鼠结膜下（SCon）间隙的P815细胞会迅速被排斥。尽管结果差异很大，但AC和SCon肿瘤在引流的颈部淋巴结内均能引发肿瘤特异性前体细胞毒性T细胞（pTc）同等程度的克隆扩增。此外，肿瘤特异性pTc会发生全身迁移，并浸润含有AC和SCon肿瘤的眼睛。本研究探讨了这样一种假说，即响应AC P815肿瘤产生的pTc作为“杀手”的效率低于其SCon对应物。为了解决这个问题，在体外利用外源性淋巴因子重新刺激pTc，以启动pTc向功能完全成熟的细胞毒性T细胞（Tc）的终末分化。然后开发了一种检测方法，以评估AC和SCon CD8 + Tc清除体外生长的P815肿瘤细胞的能力，即实现“治愈”。该检测方法确定了肿瘤细胞被完全清除（治愈）的日期以及肿瘤细胞清除率。通过这种方法发现，从携带AC和SCon肿瘤的小鼠中收获的pTc在体外清除P815肿瘤细胞的潜力相同。此外，发现如果在将效应淋巴细胞添加到增殖的肿瘤靶细胞时，在培养物中加入外源性淋巴因子作为T细胞“辅助”的替代来源，实现体外肿瘤“治愈”的效率会显著提高。后一个发现强调了持续提供辅助因子的必要性，以便最大限度地提高Tc清除肿瘤细胞的效率。我们将这些结果解释为意味着体内肿瘤的成功排斥可能取决于：（a）肿瘤特异性pTc到达肿瘤部位；（b）提供促进这些细胞终末转化为Tc的“辅助”；（c）持续存在促进肿瘤细胞免疫清除效率的“辅助”。由于在BALB/c小鼠中，等量的P815特异性pTc进入AC和SCon肿瘤部位，前者排斥失败可能是由于宿主无法提供即时和持续的局部T细胞辅助。讨论了这些研究对眼内肿瘤免疫治疗发展的意义。
