Notter M, Ludwig W D, Bremer S, Thiel E
Department of Hematology and Oncology, Free University of Berlin, Klinikum Steglitz, Germany.
Blood. 1993 Nov 15;82(10):3113-24.
The potential of the CD3 monoclonal antibody (MoAb) OKT3 to selectively target lymphokine-activated killer (LAK) cells and T-cell clones in vitro against autologous tumor cells was studied using material from patients with acute leukemias (19 acute myeloid leukemias [AML], and 3 acute lymphoblastic leukemias [ALL]). Cytotoxicity mediated by patient LAK cells against AML blasts, but not against ALL cells and autologous Epstein-Barr virus-transformed B cells, was enhanced 1.5-fold to 9.3-fold by OKT3 in all AML patients studied. The following findings suggest that the major target molecule on AML cells for OKT3-coated LAK cells is the high-affinity Fc receptor for IgG (Fc gamma RI; CD64): (1) susceptibility to killing by OKT3-coated effector LAK cells segregated with target cell expression of CD64; (2) preincubation of AML blasts with monomeric OKT3 (murine IgG2a), the Fc portion of which is known to have preferential binding affinity to CD64, resulted in lysis by autologous T cells that were not spontaneously cytotoxic; (3) OKT3-dependent increase in lysis of primary and relapsed AML cells by autologous T-cell clones correlated with the amount of target cell expression of CD64; (4) anti-leukemic cytotoxicity of OKT3-coated T cells could partially be inhibited by monomeric human Ig, the natural ligand of CD64; and (5) expression of CD64 (Fc gamma RI) on fresh AML cells could be increased by interferon-gamma (IFN-gamma) and IFN-alpha translating into further enhancement of lysis by autologous OKT3-coated LAK cells. Nonmalignant CD34+ cells sorted from peripheral blood were found to lack expression of CD64 and hence were not affected by OKT3-triggered T-cell targeting, as detected by colony formation assays. In conclusion, the in vitro data presented provide a rationale for the combined clinical use of recombinant interleukin-2, IFN-gamma, and low doses of CD3 MoAb to eliminate AML cells while sparing nonmalignant hematopoietic progenitor cells, for example, in the setting of purging procedures for autologous bone marrow transplantation.
利用急性白血病患者（19例急性髓细胞白血病[AML]和3例急性淋巴细胞白血病[ALL]）的材料，研究了CD3单克隆抗体（MoAb）OKT3在体外选择性靶向淋巴因子激活的杀伤（LAK）细胞和T细胞克隆以对抗自体肿瘤细胞的潜力。在所有研究的AML患者中，OKT3使患者LAK细胞介导的针对AML母细胞的细胞毒性增强了1.5倍至9.3倍，但对ALL细胞和自体爱泼斯坦-巴尔病毒转化的B细胞无增强作用。以下发现提示，OKT3包被的LAK细胞对AML细胞的主要靶分子是IgG的高亲和力Fc受体（FcγRI；CD64）：（1）被OKT3包被的效应LAK细胞杀伤的敏感性与靶细胞CD64的表达相关；（2）AML母细胞与单体OKT3（鼠IgG2a）预孵育，已知其Fc部分对CD64具有优先结合亲和力，导致被非自发细胞毒性的自体T细胞裂解；（3）OKT3依赖的自体T细胞克隆对原发性和复发性AML细胞裂解的增加与靶细胞CD64的表达量相关；（4）OKT3包被的T细胞的抗白血病细胞毒性可被单体人Ig（CD64的天然配体）部分抑制；（5）新鲜AML细胞上CD64（FcγRI）的表达可被干扰素-γ（IFN-γ）和干扰素-α增加，这转化为自体OKT3包被的LAK细胞裂解的进一步增强。通过集落形成试验检测发现，从外周血中分选的非恶性CD34+细胞缺乏CD64表达，因此不受OKT3触发的T细胞靶向作用的影响。总之，本文提供的体外数据为联合临床使用重组白细胞介素-2、IFN-γ和低剂量CD3 MoAb以消除AML细胞同时保留非恶性造血祖细胞提供了理论依据，例如在自体骨髓移植的净化程序中。
