Lymphocyte Phenotyping and HLA-DR Expression over the Course of COVID-19 Infection in Patients with Different Disease Severity.

Background: The role of lymphocyte subsets in the diagnosis and follow up of COVID-19 is still unclear. So, we aim to study the changes in lymphocyte subsets and HLA-DR expression in the peripheral blood of hospitalized COVID-19 patients.

Methods: Lymphocyte subsets and HLA-DR expression were detected in the peripheral blood of 36 hospitalized patients of COVID-19; their data were compared to that of 36 healthy controls of comparable age and gender.

Results: Total lymphocytes, the percentage of CD3 T, CD4 T and CD8 T cells significantly decreased, while that of CD 56 cells significantly increased in SARS-CoV-2 infected patients. The expression of HLA-DR is down regulated in these cells. Neutrophil/lymphocyte ratio, neutrophil/CD3 ratio, neutrophil/CD4 ratio, and neutrophil/CD8 ratio are significantly increased in patients compared with controls. The absolute count of CD3, CD4, CD8 and CD19 cells, significantly decreased in SARS-CoV-2 infected patients.

Conclusions: A marked reduction in CD8+T and CD4+T count together with HLA-DR cell expression with obvious impairment in cellular immunity has been detected in patients with more severe impairment and progressive course for the disease.