Levels of peripheral IL-6 and CD4+ and CD8+ T cells and their prognostic significance in COVID-19

The aim of this study was to discuss the prognostic significance of peripheral interleukin-6 (IL-6) and CD4+ and CD8+ T cells in COVID-19.

Eighty-four COVID-19 patients were retrospectively analyzed and classified into three groups, including the moderate group (15 cases), the serious group (45 cases), and the critical group (24 cases). The levels of peripheral IL-6, CD4+, and CD8+ T cells and CD4+/CD8+ were determined for each group. It was assessed whether these indicators were correlated to the prognosis and death risks of COVID-19 patients.

The three groups of COVID-19 patients differed significantly in the levels of peripheral IL-6 and CD4+ and CD8+ cells. The IL-6 levels in the critical, moderate, and serious groups were increased successively, but the changed levels of CD4+ and CD8+ T cells were just opposite to that of IL-6 (p<0.05). The peripheral IL-6 level increased dramatically in the death group, while the levels of CD4+ and CD8+ T cells decreased significantly (p<0.05). The peripheral IL-6 level was significantly correlated with the level of CD8+ T cells and CD4+/CD8+ ratio in the critical group (p<0.05). The logistic regression analysis indicated a dramatic increase in the peripheral IL-6 level in the death group (p=0.025).

The aggressiveness and survival of COVID-19 were highly correlated with the increases in IL-6 and CD4+/CD8+ T cells. The fatalities of COVID-19 individuals remained at increased incidence due to elevated peripheral IL-6 levels.