- This study was conducted in 522 COVID-19 patients (age between 5 days -97 years) admitted in Hanyang hospital in Wuhan, China and 40 healthy people (aged between 2-62 years) who came to hospital for routine physical examination.
- In all patients, number of CD8+ T-cells were drastically reduced, and T-cells were also exhausted. In ICU admitted patients, 95% of patients showed decrease in both T-cells and CD8+ T-cells. In Non-ICU patients, around 71% cases had a decrease in total, CD4+ and CD8+ T cells.
- T-cells play a vital role in viral clearance. CD8+ cytotoxic T-cells help to eradicate viruses from the host by secreting molecules like INF-ϒ and granzymes. CD4+ helper T-cells can assist cytotoxic T-cells and B-cells and enhance their ability to fight against pathogens.
- It is also found that the secretion of cytokines including TNF-α, IL-6, and IL-10 was increased in COVID-19 patients.
- T-cell exhaustion may be caused due to persistent virus stimulation which may lead to loss of cytokine production and reduced function.
- Researchers have assumed that cytokines like IL-6 (Interleukin), IL-10 and TNF-α might be involved in T-cell reduction. So, new therapeutic measures may be needed to treat COVID-19 ICU patients or may be necessary even early to inhibit progression of disease in higher risk patients.
Reference
Diao B, Wang C, Tan Y, Chen x, Liu Y. Reduction and Functional Exhaustion of T Cells in Patients with Coronavirus Disease 2019 (COVID-19). Frontiers in Immunology. 2020;11 (827):1-7.