Evaluation of lymphocyte subtypes in COVID-19 patients

BackgroundAlthough the many aspects of COVID-19 have not been yet recognized, it seems that the dysregulation of the immune system has a very important role in the progression of the disease. In this study the lymphocyte subsets were evaluated in COVID-19 patients with different severity. MethodsIn this prospective study, the levels of peripheral lymphocyte subsets (CD3+, CD4+, CD8+ T cells; CD19+ and CD20+ B cells; CD16+/CD56+ NK cells, and CD4+/CD25+/FOXP3+ regulatory T cells) were measured in 67 confirmed patients with COVID-19 on the first day of admission. ResultsThe mean age of cases was 51.3 {+/-} 14.8 years. Thirty-two patients (47.8%) were classified as severe cases and 11 (16.4%) patients were categorized as critical. The frequency of blood lymphocytes, CD3+ cells, CD25+FOXP3+ T cells; and absolute count of CD3+ T cells, CD25+FOXP3+ T cells, CD4+ T cells, CD8+ T cells, CD16+56+ lymphocytes were lower in more severe cases in comparison to milder cases. Percentages of lymphocytes, T cells, and NK cells were significantly lower inthe patients who died (p= 0.002 and P= 0.042, p=0.006, respectively). ConclusionFindings of this cohort study suggests that the frequency of CD4+, CD8+, CD25+FOXP3+ T cells, and NK cells were difference in the severe COVID-19 patients. Moreover, lower frequency of, T cells, and NK cells are predictors of mortality of these patients.