Characteristics of Peripheral Lymphocyte Subset Alteration in COVID-19 Pneumonia

Wang F, Nie J, Wang H, et al. Characteristics of Peripheral Lymphocyte Subset Alteration in COVID-19 Pneumonia. J Infect Dis. 2020;221(11):1762‐1769. doi:10.1093/infdis/jiaa150

Review written by:

Ignacio Hernández-Morato, edited by Rinki Saha

Yellow - Strong evidence. Analysis of immune cell types proportion in COVID-19 patients compared to healthy samples

INTRODUCTION: Viral infection with SARS-CoV-2 has been shown to lead to a decrease in overall lymphocytes, but subtype specific effects are still unknown. The aim of this study is to evaluate alterations of specific lymphocyte populations in COVID-19 patients.

METHODS: Blood samples from 60 COVID-19 patients were analyzed, 19 of which were characterized as severe illness. 2mL of blood were collected from the patients before and after 1 week of treatment. CD3/CD4/CD8 T-cells, CD19 B-cells, and CD16 CD56 NK-cells were quantified by flow cytometry using the following antibodies: anti-CD3-fluorescein isothiocyanate, anti-CD4-phycoerythtin, anti-CD8-allophycocyanin, anti-CD19-phycoerythrin, anti-CD16- allophycocyanin, and anti-CD56- phycoerythrin (BD Biosciences). Analyses were processed using SPSS.

RESULTS: Prior to treatment, which varied by patient, blood tests of COVID-19 patients showed varied levels of leukocytes (32% below and 11% above normal range), neutrophils (21% below and 13% above normal range), and platelets (21% below and 2% above normal range). Total number of lymphocytes were significantly lower in COVID-19 patients compared to the healthy controls. Lymphocyte number was especially reduced in patients with severe disease.. After treatment, lymphocytes levels grew to control levels except for CD4+ T cells, the CD4+/CD8+ ratio, and NK cells, which remained abnormal. When subsetting results by treatment, corticosteroid treatments increased the number of lymphocytes dramatically, while antiviral treatments increased only CD4+ T cells, CD8+ T cells, and B cells.

Review Notes

The present study was well constructed, and the experiments were sound to the aim of the study. However, one downside of this study is the limited number of samples analyzed and the varied treatments reducing the power to identify treatment specific changes.

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