Strategies to reverse T-cell exhaustion
As mentioned above, CD8+ T cells and NKT cells expressed high levels of the inhibitory membrane receptors in sever COVID-19 patients, including PD-1, CLTA4, Tim-3 and so on [58, 66, 74]. Therefore, targeting PD-1, CLTA4, Tim-3 and other inhibitory membrane receptors could be beneficial in releasing the brake of T‐cell exhaustion to enhance T cell responses. Four clinical trials to evaluate the effectiveness of anti-PD-1 antibody administration in COVID-19 patients are ongoing [96].