Lymphocyte Subset Counts in COVID-19 Patients: A Meta-Analysis

Abstract

A reduced peripheral blood absolute lymphocyte count with an elevated neutrophil count has been a consistent observation in hospitalized coronavirus disease 2019 (COVID-19) patients. In this brief meta-analysis, the reduction of lymphocyte subset counts in COVID-19 patients was investigated across 20 peer-reviewed studies meeting criteria for reporting lymphocyte subset counts and COVID-19 disease severity. CD4+ T cell, CD8+ T cell, B cell, NK cell, and total lymphocyte cell counts all showed statistically significant reduction in patients with severe/critical COVID-19 disease compared to mild/moderate disease. T-cell subsets showed the largest standardized magnitude of change. In some studies, multivariate analysis has shown that CD4 and/or CD8 T-cells counts are independently predictive of patient outcomes. © 2020 International Society for Advancement of Cytometry.

Keywords: COVID-19; T-cell subset; flow cytometry; immunophenotyping; lymphocyte subset.

Figure 1

Mean cell counts for each individual lymphocyte subset in mild/moderate and severe/critical COVID‐19 patients across articles. Each solid circle represents the mean cell count in one article and the size of the circle represents the relative sample size for the mean. Paired data points from the same article are connected. The weighted mean value of cell counts across all articles is also shown with 95% confidence interval (CI) based on the random variability across articles. [Color figure can be viewed at wileyonlinelibrary.com]

Figure 2

Standardized mean differences (SMDs) between mild/moderate and severe/critical disease groups, with 95% confidence interval (95%CI), in COVID‐19 patients. There is one panel for total lymphocytes, as well as panels for each subset. SMDs with CI results on the left of the 0 vertical line indicate a negative difference, i.e., the average mean count in the severe/critical group was significantly lower than in the mild/moderate group. Note that the width of the individual CIs is a function of sample size and reported variability within each publication.