1.Evidence of the dysregulated immune response in COVID-19 infection:
A cohort study of 452 patients with laboratory-confirmed COVID-19 in Wuhan, China, reported a dysregulated immune response in these patients. As a result of this suppressed immune response, the increase of neutrophil to lymphocyte ratio (NLR), T lymphopenia, and decrease of CD4+ T cells were considered as common laboratory findings, especially in severe cases. However, there was no significant change in the number of CD8+ cells and B cells. According to these data, lymphocyte damage, especially T lymphocytes, seems to be one of the most important disease pathogenesis factors. It is suggested that the amount of lymphocyte injury (mainly T lymphocyte) and subsequent cellular immune suppression are a critical factor in disease progression(14).
Furthermore, another study in Wuhan, China, also confirmed the relationship between T cell count and disease prognosis. According to this research, patients with a total T cell count lower than 800/µl generally require more aggressive interventions and ICU admission(15).