ABSTRACT
Background: Immune dysregulation plays a key role in determining COVID-19 disease severity. We aimed to analyze the T cell activation profile in COVID - 19 cases and its predictive role in disease severity and outcome. Material & methods: This was a prospective observational pilot study from a tertiary care COVID-19 hospital. Peripheral blood samples obtained between the fifth and seventh day of COVID-19 illness, were subjected to lymphocyte subset analysis using multicolor flowcytometry using a single tube, 8 antibodies (CD45, CD19, CD3, CD4, CD8, CD38, HLADR, and CD56) analysis. Correlation between lymphocyte subset analysis and clinical profile was determined. Results: 26 patients including 11 with mild disease and 15 with severe disease were enrolled. The median age was 58 years (range: 33-81), with a male: female ratio of 1.36:1. Significant lymphopenia was observed in the severe group compared to the mild group (p < 0.02). The absolute numbers of CD3+, CD4+, CD8 + T cells, B cells, and NK cells were significantly reduced in the severe group as compared to the mild group (p < 0.05). In patients with severe disease, the proportion of CD8 + and CD4 + T cells were significantly higher than those in patients with mild disease (p = 0.0372). Using ROC analysis, a CD4:8 T cell ratio of ≥ 2.63 and an activated (CD38 + HLA-DR+) CD8 T cell proportion of > 15.85% of the total CD8 T cell population, significantly determined the severe disease category. Conclusions: Severe COVID-19 is associated with severe lymphopenia, altered CD4/CD8 ratio and markedly increased CD8 T cell activation profile. Supplementary Information: The online version contains supplementary material available at 10.1007/s12288-022-01558-6.