Fresenius Biotech GmbH, Frankfurter Ring 193a, 80807 Munich, Germany.
Clin Transl Oncol. 2012 May;14(5):376-81. doi: 10.1007/s12094-012-0811-5.
In patients, a transient decrease in peripheral blood lymphocyte counts was observed following intraperitoneal administration of the trifunctional monoclonal antibody catumaxomab (anti-human EpCAM x anti-human CD3). The aim of this study was to clarify the observed effect in a preclinical mouse model and to analyse the related mechanism of action in vitro.
A related antibody, BiLu (antihuman EpCAM x anti-mouse CD3), was administered to mice and blood leukocytes were analysed. In vitro studies measured activation and cytokine secretion from human peripheral blood mononuclear cells (PBMC). For the analysis of T cell adhesion, PBMC were preincubated with catumaxomab and then co-cultured with human endothelial cells (HUVEC); T cell adhesion was assessed in the presence or absence of endothelial cell preactivation by TNFα. Adherent T cells were determined by flow cytometry.
Treatment of mice with BiLu resulted in a dosedependent transient decrease in CD3+ T cells (both CD4+ and CD8+) that returned to the normal range within 48 h. Catumaxomab physiologically activated T cells in vitro (increased CD69 expression) and induced cytokine release (TNFα, IFNγ). TNFα increased expression of adhesion molecules CD54 and CD62E on endothelial cells. Furthermore, catumaxomab dose-dependently enhanced adhesion of T cells to endothelial cells. Adhesion was further increased when endothelial cells were preactivated with TNFα.
Catumaxomab increases adhesion of T cells to endothelial cells due to antibody-mediated activation of T cells and production of T cell cytokines that up-regulate endothelial cell adhesion molecules. These results provide a mechanistic rationale for the transient, reversible decrease in lymphocyte counts observed following catumaxomab administration in patients, which is likely to be due to redistribution of lymphocytes.
在患者中，腹腔内给予三功能单克隆抗体 catumaxomab（抗人 EpCAM x 抗人 CD3）后，外周血淋巴细胞计数短暂下降。本研究旨在澄清在临床前小鼠模型中观察到的效应，并分析体外相关作用机制。
给小鼠注射相关抗体 BiLu（抗人 EpCAM x 抗鼠 CD3），并分析血液白细胞。体外研究测量人外周血单核细胞（PBMC）的活化和细胞因子分泌。为了分析 T 细胞黏附，将 PBMC 与 catumaxomab 预孵育，然后与人内皮细胞（HUVEC）共培养；在 TNFα 预激活内皮细胞的存在或不存在的情况下，评估 T 细胞黏附。通过流式细胞术测定黏附的 T 细胞。
用 BiLu 处理小鼠导致 CD3+T 细胞（CD4+和 CD8+）剂量依赖性短暂下降，在 48 小时内恢复正常范围。Catumaxomab 在体外生理性地激活 T 细胞（增加 CD69 表达）并诱导细胞因子释放（TNFα、IFNγ）。TNFα 增加内皮细胞上黏附分子 CD54 和 CD62E 的表达。此外，Catumaxomab 剂量依赖性地增强 T 细胞与内皮细胞的黏附。当内皮细胞用 TNFα 预激活时，黏附进一步增加。
Catumaxomab 通过抗体介导的 T 细胞活化和产生 T 细胞细胞因子，增加 T 细胞与内皮细胞的黏附，从而上调内皮细胞黏附分子。这些结果为患者接受 catumaxomab 治疗后观察到的淋巴细胞计数短暂、可逆下降提供了机制依据，这可能是由于淋巴细胞重新分布所致。
