Jahnsen F L, Brandtzaeg P, Halstensen T S
Laboratory for Immunohistochemistry and Immunopathology (LIIPAT), University of Oslo, Norway.
J Immunol Methods. 1994 Sep 30;175(1):23-36. doi: 10.1016/0022-1759(94)90328-x.
The monoclonal antibody (mAb) EG2 has been considered to identify activated eosinophils and several immunohistochemical reports of EG2+ eosinophils in various allergic and other inflammatory disorders have suggested an important pathogenic role for such cells. This study showed that cellular EG2 reactivity, both in peripheral blood and mucosal tissue preparations, depends mainly on the method of sample preparation. Nearly 100% of blood eosinophils from normal individuals were strongly EG2+ when prepared by formalin fixation, whereas only a fraction reacted in the unfixed (64%) or acetone-fixed (60%) state. A significantly increased (p < 0.03) number of EG2+ cells were likewise detected in cryo-sections of inflamed nasal mucosa after formalin fixation compared with acetone fixation. Moreover, virtually all eosinophils were EG2+ in cryo-sections of normal jejunal mucosa fixed in periodate-lysine-(0.5%) paraformaldehyde prior to freezing. Conversely, EG2 reacted only weakly, or failed to react, with many eosinophils in cryo-material not subjected to such pre-fixation, in contrast to adjacent non-eosinophilic cells which were brightly stained. Two-colour immunofluorescence consistently revealed overlapping labelling with EG2 and mAb EG1 or a polyclonal antibody to eosinophil cationic protein in sections of formalin-fixed, paraffin-embedded normal gastrointestinal mucosa. Our findings thus showed that EG2 does not provide reliable immunohistochemical discrimination between resting and activated eosinophils. When optimal pre-fixation of tissue specimens was omitted, EG2 reactivity appeared to be caused, at least in part, by leached antigen adsorbed to adjacent non-eosinophilic cells.
单克隆抗体（mAb）EG2 被认为可识别活化的嗜酸性粒细胞，多项关于 EG2 阳性嗜酸性粒细胞在各种过敏性和其他炎症性疾病中的免疫组织化学报告表明，此类细胞具有重要的致病作用。本研究表明，外周血和黏膜组织标本中的细胞 EG2 反应性主要取决于样本制备方法。正常个体的血液嗜酸性粒细胞经福尔马林固定后，近 100% 呈强 EG2 阳性，而在未固定（64%）或丙酮固定（60%）状态下只有一部分发生反应。与丙酮固定相比，福尔马林固定后发炎鼻黏膜的冷冻切片中检测到的 EG2 阳性细胞数量显著增加（p < 0.03）。此外，在冷冻前用高碘酸盐 - 赖氨酸 -（0.5%）多聚甲醛固定的正常空肠黏膜冷冻切片中，几乎所有嗜酸性粒细胞均为 EG2 阳性。相反，在未进行这种预固定的冷冻材料中，许多嗜酸性粒细胞与 EG2 的反应较弱或无反应，而相邻的非嗜酸性细胞则被明亮染色。双色免疫荧光始终显示，在福尔马林固定、石蜡包埋的正常胃肠道黏膜切片中，EG2 与 mAb EG1 或嗜酸性粒细胞阳离子蛋白的多克隆抗体存在重叠标记。因此，我们的研究结果表明，EG2 不能在静止和活化的嗜酸性粒细胞之间提供可靠的免疫组织化学鉴别。当省略组织标本的最佳预固定时，EG2 反应性似乎至少部分是由吸附在相邻非嗜酸性细胞上的浸出抗原引起的。
