1、托珠单抗治疗新冠肺炎的基本原理是什么？

新冠肺炎患者体内大量T淋巴细胞和单核巨噬细胞被激活，产生白细胞介素-6（IL-6）等细胞因子，与靶细胞上的IL-6受体结合，引起细胞因子风暴，导致肺部等组织器官出现严重炎症反应。托珠单抗是特异性阻断IL-6受体的抗体，可与IL-6受体产生高亲和性结合，从而阻止IL-6本身与其受体无法结合，失去对靶细胞的免疫损伤作用，缓解炎症反应的发生。

2、托珠单抗治疗新冠肺炎的适应症是什么？

由于托珠单抗阻止IL-6引起的炎症风暴，所以在轻症患者向重症发展，或已发展为重症患者时及时使用，会取得很好疗效。肺部已出现大面积严重不可逆损伤等危重症患者，使用效果一般。

3、托珠单抗治疗新冠肺炎之前需要检测白细胞介素-6吗？

检测IL-6是使用托珠单抗的基本要求，由于IL-6主要聚集在肺脏等组织器官，血液中含量不一定很高，因此，只要检测到IL-6升高即可使用（>7pg/ml）。特殊条件下不能检测IL-6时，如果病情急需，可参考CRP值升高，由医生酌情考虑使用。

4、为什么使用托珠单抗治疗新冠肺炎之后白细胞介素-6会升高？

由于托珠单抗是特异性阻断IL-6受体的抗体，使IL-6本身与其受体无法再结合，从而大量游离到血液中，检测IL-6时反而会升高，但一周后会逐渐降低至正常。

5、托珠单抗治疗新冠肺炎的禁忌症是什么？

过敏体质。结核等活动性感染患者禁止使用。

6、托珠单抗治疗新冠肺炎的安全性如何？

目前，使用托珠单抗治疗超过四百例病人，除一例过敏反应需要对症处理，少数白细胞下降、皮肤瘙痒等一过性症状会自然缓解。总体安全可靠。（中国科学技术大学生命科学与医学部  魏海明）

Q&A on Treatment of COVID-19 with Tocilizumab

1. What is the basic principle of treating of COVID-19 with Tocilizumab?

In patients with COVID-19, a large number of T lymphocytes and mononuclear macrophages are activated, producing cytokines such as interleukin-6 (IL-6) which bind to the IL-6 receptor on the target cells, causing the cytokine storm and severe inflammatory responses in lungs and other tissues and organs. Tocilizumab is an antibody specifically blocking the IL-6 receptor, which can bind to the IL-6 receptor with high affinity, thus preventing IL-6 itself from binding to its receptor, rendering it incapable of immune damage to target cells, and alleviating the inflammatory responses.

2. What are the indications for treating COVID-19 with Tocilizumab?

Since Tocilizumab prevents the cytokine storm caused by IL-6, timely use of Tocilizumab in mild cases when they progress to or have become severe cases will achieve good results. For critical patients with extensive and severe irreversible damage to the lungs, the effect is moderate.

3. Is it necessary to detect IL-6 before treating COVID-19 with Tocilizumab?

Detection of IL-6 is a basic requirement for the use of Tocilizumab. Since IL-6 is mainly concentrated in tissues and organs such as the lungs, its level is not necessarily high in blood. So Tocilizumab can be used whenever the elevated IL-6 level is detected (>7pg/ml). When IL-6 can’t be detected under special conditions, if the condition is urgent, the doctor may consider using Tocilizumab as appropriate by referring to the elevated CRP value.

4. Why does the IL-6 level increase after treatment of COVID-19 with Tocilizumab?

Tocilizumab is an antibody that specifically blocks the IL-6 receptor, so that IL-6 itself can no longer bind to its receptor and goes into the blood in large quantities. So the Il-6 level is elevated when detected, but it will gradually decrease to the normal level after one week.

5. What are the contraindications for treating COVID-19 with Tocilizumab?

Tocilizumab is contraindicated in patients with allergic constitution, tuberculosis and other active infections.

6. Is it safe to treat COVID-19 with Tocilizumab?

Currently, more than 400 patients have been treated with Tocilizumab. One patient developed anaphylaxis that required symptomatic treatment. A few patients had transient symptoms such as decrease of white blood cells and skin itching, which would relieve naturally. Tocilizumab is generally safe and reliable.

（科大讯飞/翻译  中国科学技术大学生命科学与医学部 魏海明/审核）