Peripheral Blood Lymphocyte Immunophenotypes among COVID-19 Patients with Different Severity

Background: The COVID-19 pandemic poses an urgent need to understand the role of host immunity in viral infection. The disrupted immune response can cause alteration of peripheral blood lymphocytes in COVID-19 patients. The study was aimed to quantify and compare the peripheral blood lymphocytes including CD3+ T cells, CD4+ T cells, CD8+ T cells, B cells and Natural killer cells among COVID-19 patients with different clinical severity and healthy subjects. Methodology: The study was conducted from March 2020 to January 2021 in the Department of Microbiology and Immunology, Bangabandhu Sheikh Mujib Medical University. A total of 103 laboratory-confirmed COVID-19 patients and 20 healthy subjects were enrolled. COVID-19 patients were clinically categorized into asymptomatic (n=18), mild-moderate (n=38) and severe-critical (n=47) group. Peripheral venous blood samples were collected from study groups and immunophenotyping was done by flow cytometry. Statistical analysis was done by one way ANOVA test. Results: The percentages of total peripheral lymphocytes as well as T lumphocytes were significantly decreased in severe-critical group than in mild-moderate, healthy and asymptomatic group (P<.001). Furthermore, percentage of T cell including CD4+ T cell and CD8+ T cell counts were also significantly decreased in severe-critical group than other three study groups (P<.001). Percentage NK cell was lower and B cell was higher in severe-critical group. Conclusion: The total lymphocyte and T cells including, CD4+ T cells, CD8+ T cells in peripheral blood could be used as biomarkers for identifying severe COVID-19 patients. Bangladesh Med Res Counc Bull 2024; 50: 148-154