Dynamics of peripheral immune cells and their HLA-G and receptor expressions in a patient suffering from critical COVID-19 pneumonia to convalescence

Abstract Objectives Host immune responses are indispensable to combat the disease We report the dynamics of peripheral immune cells, cytokines, and human leucocyte antigen-G (HLA-G) and its receptor expressions in a patient suffering from critical COVID-19 pneumonia to convalescence Methods Clinical data of the patient were collected from medical records The expressions of HLA-G and receptors ILT2, ILT4 and KIR2DL4 in peripheral immune cells were measured with flow cytometry Results From critical COVID-19 to the convalescent stage, early lymphopenia was improved (median: 0 6�?�109�L?1 vs 0 9�?�109�L?1, P�=�0 009), and an obvious fluctuation in WBC and neutrophil counts was observed Initially, low levels of CD4+ T cells (from 120 to 528�?L?1) and CD8+ T cells (from 68 to 362�?L?1) gradually increased to normal levels Meanwhile, high IL-6 (from 251 8 to 6 32�pg�mL?1), IL-10 (from 39 53 to 5 21�pg�mL?1) and IFN-? (from 13 55 to 3 16�pg�mL?1) levels decreased, and IL-4 (from 2 36 to 3 19�pg�mL?1) and TNF-? (from 2 27 to 20 2�pg�mL?1) levels increased quickly when the viral RNA returned negative Moreover, the percentage of HLA-G+ T cells, B cells and monocytes follows high?low?high pattern, while the percentage of receptors ILT2-, ILT4- and KIR2DL4-expressing cells remained relatively stable Conclusion Our findings provide valuable information on the dynamics of early peripheral immunological responses in SARS-CoV-2 infection CD4+ and CD8+ T cells, cytokines and HLA-G+ immune cells are associated with the natural history of the critical COVID-19 patient;however, future studies are necessary