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First Author:  Matic Sanja et al. 

Journal/preprint name: bioRxiv 

Paper DOI 

Tags: -immune system, Innate cells, Flow cytometry 


In this paper Sanja et al. look at flow cytometry staining of whole blood from 5 healthy controls, 30 mild/moderate and 27 severe COVID-19 patients. The author found that, as previously shown, COVID-19 patients have higher neutrophils/lymphocyte ratio, as well as reduced CD19+ and NK cells. The differences are more acute in the severe patients where DC and NKs numbers were very low. Analysis of the innate cells also show a reduction in atypical CD14+ cells as well as HLA expression. The number of dendritic cells is also reduced in COVID-19 patients, especially pDCs. 

Research Highlights

  1. Immune cells profile of severe COVID-19 patients is more different from healthy control than mild/moderate ones. 

  1. Severe COVID-19 patients show reduction in atypical monocytes 

  1. Severe COVID-19 patients show reduction in CD11c+ and pDC cells 

  1. HLA-DR expression is reduced in COVID-19 patients 

  1. Expression of CD23 in innate cells is upregulated in COVID-19 patients 

Impact for COVID-19 research:  

  • This study shows that innate cells are dysregulated in COVID-19 patients 


  • Study Typepatient cohort 

  • Important cell lines/viral models used:  

  • Key Techniques: flow cytometry 


  • The study does not clarify the ages of the patients (just averages) and it is not clear if the controls are pertinent, also the patients vary widely in ages. There is no information on pre-existing conditions or medications that could affect immune cells. 

  • Lack a clear explanation of the gating strategy 

  • The figures never show the variation between samples, most graph do not have error bars 

  • The study is mostly descriptive-but there is some statistical analysis done to measure cell numbers (see methods)