key: cord-0952019-3bthgllb
authors: Teng, Jialin; Dai, Jin; Su, Yutong; Zhou, Zhuochao; Chi, Huihui; Wan, Liyan; Meng, Jianfen; Wang, Zhihong; Wang, Fan; Ma, Yuning; Hu, Qiongyi; Cheng, Xiaobing; Liu, Honglei; Ye, Junna; Shi, Hui; Sun, Yue; Yang, Chengde; Wang, Xuefeng
title: Detection of IgM and IgG antibodies against SARS-CoV-2 in patients with autoimmune diseases
date: 2020-05-18
journal: Lancet Rheumatol
DOI: 10.1016/s2665-9913(20)30128-4
sha: 2c2b45eec948c895cfe5838bff982f62c0d9f87f
doc_id: 952019
cord_uid: 3bthgllb

nan

In December, 2019, an outbreak of the novel coronavirus (SARS-CoV-2) that causes coronavirus dis ease 2019 (COVID-19) occurred in Wuhan, China, 1 and soon spread all over the world. Rapid and accurate diagnosis of SARS-CoV-2 infection is the corner stone of all efforts to stem its advance ment. Molecular detection via RT-PCR can result in falsely negative results due to the low viral loads in a sample. Serological methods are being developed and have proven to be a useful supplementary approach in confirming SARS-CoV-2 infection. 2 The US Food and Drug Administration has issued numerous Emergency Use Authorisations, including serological tests; however, the potential for crossreactivity with antibodies present in the sera of patients with other diseases remains largely unknown. Cross-reactivity of antibodies against SARS-CoV-2 with antibodies against other coronaviruses, such as SARS-CoV, has been shown. 3 In addition, cross-reactivity has been observed from auto antibodies in serum samples from patients with autoimmune disease when testing for SARS-CoV, 4 which shares high sequence identity with SARS-CoV-2. As such, we wanted to determine whether autoantibodies interfere with detection of SARS-CoV-2 antibodies.

We collected 290 serum samples from patients with autoimmune disease in our serum library, consisting of 98 patients with rheumatoid arthritis, 100 patients with systemic lupus erythematosus, and 92 patients with Sjogren's syndrome. The samples were collected from Jan 1, 2016, to June 30, 2019, which predates the COVID-19 pandemic. Written informed consent was obtained from all patients.

The serological test for SARS-CoV-2 IgM and IgG monoclonal antibodies was done with colloidal gold-labelled kits supplied by Innovita Biotechnology Co, Tangshan, China. The nitro cellulose filter of these colloidal gold-labelled assays are coated with two antigens of SARS-CoV-2 (N protein and S protein). The overall testing sensitivity was 89% (352/397) and specificity was 91% (116/128).

Our results showed that both IgG and IgM antibodies against SARS-CoV-2 were not detected in the serum of patients with autoimmune disease, indicating that there was no crossreactivity between autoantibodies and SARS-CoV-2 antibodies (table) . It should be noted, however, that these sera were only analysed using one kit and other kits with different test operating characteristics might produce different results.

In conclusion, the serological test we assessed showed no cross-reactivity with autoantibodies present in patients with autoimmune disease. Asymptomatic carriers could spread SARS-CoV-2, 5 and this type of test could make large scale screening of asymptomatic SARS-CoV-2 carriers possible. We propose that serological testing of IgM and IgG antibodies, along with RT-PCR, in clinical prac tice should help provide an accurate COVID-19 diagnosis, including in patients with autoimmune disease.

We declare no competing interests. We appreciate all the participants and students who took part in this study. This research was not funded. Patients consent for publication was not required. 

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Cross-reaction of SARS-CoV antigen with autoantibodies in autoimmune diseases

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