Immunophenotyping characteristics of COVID-19 patients: Peripheral blood CD8+ HLA-DR+ T cells as a biomarker for mortality outcome.

Abstract

The goal of this study was to identify biomarker(s) to assign risk of mortality in COVID-19 patients to improve intensive care unit(ICU) and coronary care unit management.A total of 100 confirmed COVID-19 patients admitted at Imam Khomeini Hospital in Tehran, were compared to 70 control subjects. Peripheral blood leukocyte was studied using staining reagents included CD3, CD4, CD8, HLA-DR, CD19, CD16, and CD56. The immunophenotyping analysis was evaluated using the FACSCalibur instrument. To investigate the cell density of lung infiltrating T cells, postmortem slides of needle necropsies taken from the lung tissue of 3critical patients were evaluated by immunohistochemistry staining.The number of lymphocyte subpopulations was significantly lower in COVID-19 patients than in the control group. Regarding the disease severity, the absolute count of T, NK, and HLA-DR+ T cells were significantly reduced in severe patients compared to the moderate ones. The critical patients had a significantly lower count of CD8-HLA-DR+ T cells than the moderate cases. Regarding the disease mortality, based on univariate analysis, the count of HLA-DR+ T, CD8-HLA-DR+ T, and CD8+ HLA-DR+ T cells was associated with mortality in COVID-19 patients. Receiver operating characteristiccurve analysis showed the count of CD8+HLA-DR+ T cells is the best candidate as a biomarker for mortality outcome. Furthermore, pulmonary infiltration of T cells in the lung tissue showed only slight infiltrations of CD3+ T cells, with an equal percentage of CD4+ and CD8+ T cell subpopulation in the lung tissue.These findings suggest that close monitoring of the value of CD8+HLA-DR+ T cells in COVID-19 patients may be helpful to identify high-risk patients. However, further studies with larger sample size are needed.