Analysis of Lymphocyte Subpopulations and Cytokines in COVID-19-Associated Pneumonia and Community-Acquired Pneumonia

The 2019 novel coronavirus SARS-CoV-2 caused large outbreaks of COVID-19 worldwide. COVID-19 resembles community-acquired pneumonia (CAP). Our aim was to identify lymphocyte subpopulations to distinguish between COVID-19 and CAP.

We compared the peripheral blood lymphocytes and their subsets in 296 patients with COVID-19 and 130 patients with CAP. Parameters for independent prediction of COVID-19 were calculated by logistic regression.

The main lymphocyte subpopulations (CD3⁺CD4⁺, CD16⁺CD56⁺, and CD4⁺/CD8⁺ ratio) and cytokines (TNF-α and IFN-γ) of COVID-19 patients were significantly different from that of CAP patients. CD16⁺CD56⁺%, CD4⁺/CD8⁺ratio, CD19⁺, and CD3⁺CD4⁺ were identified as predictors of COVID-19 diagnosis by logistic regression. In addition, the CD3⁺CD4⁺counts, CD3⁺CD8⁺ counts, andTNF-α are independent predictors of disease severity in patients.

Lymphopenia is an important part of SARS-CoV-2 infection, and lymphocyte subsets and cytokines may be useful to predict the severity and clinical outcomes of the disease.