Immune phenotyping based on neutrophil-to-lymphocyte ratio and IgG predicts disease severity and outcome for patients with COVID-19

Bicheng Zhang; Xiaoyang Zhou; Chengliang Zhu; Fan Feng; Yanru Qiu; Jia Feng; Qingzhu Jia; Qibin Song; Bo Zhu; Jun Wang

All patients had convalescent-phase sera for analysis. Of these, 98.6% of patients had anti-SARS-CoV-2-IgG detected in sera, and 82.0% had anti-SARS-CoV-2-IgM detected in sera. As shown in figure 1A , IgG was first detected on day 4 of illness, and its peak levels occurred in the fourth week, whereas IgM was first detected on day 3 of illness, and its peak levels occurred in the second week. Median IgG and IgM levels in convalescent-phase sera (within 35 days) for all included patients were compared among severe and nonsevere patients. Higher IgM levels were detected in patients with severe disease compared to those with nonsevere disease at early stage (<14 days), whereas higher IgG levels were detected at late stage (≥21 days) (figure 1B and 1C). We used median as cut-off value to stratify high and levels of IgM and IgG. Interestingly, severe cases were more frequently occurred in patients with low IgM levels (<34.1 AU/mL) than those with high IgM levels (≥3.04 AU/mL) (81.3% versus 40%; p=0.024) ( figure 1D ). Severe cases were more frequently found in patients with high IgG levels (≥116.9 AU/mL), compared to those who with low IgG levels (<116.9 AU/mL) (51.8% versus 32.3%; p=0.008) (figure 1E).