The contributory role of lymphocyte subsets, pathophysiology of lymphopenia and its implication as prognostic and therapeutic opportunity in COVID-19

The incidence of the novel coronavirus disease (COVID-19) outbreak caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has brought daunting complications for people as well as physicians around the world. An ever-increasing number of studies investigating the characteristics of the disease, day by day, is shedding light on a new feature of the virus with the hope that eventually these efforts lead to the proper treatment. SARS-CoV-2 activates antiviral immune responses, but in addition may overproduce proinflammatory cytokines, causing uncontrolled inflammatory responses in patients with severe COVID-19. This condition may lead to lymphopenia and lymphocyte dysfunction, which in turn, predispose patients to further infections, septic shock, and severe multiple organ dysfunction. Therefore, accurate knowledge in this issue is important to guide clinical management of the disease and the development of new therapeutic strategies in patients with COVID-19. In this review, we provide a piece of valuable information about the alteration of each subtype of lymphocytes and important prognostic factors associated with these cells. Moreover, through discussing the lymphopenia pathophysiology and debating some of the most recent lymphocyte- or lymphopeniarelated treatment strategies in COVID-19 patients, we tried to brightening the foreseeable future for COVID19 patients, especially those with severe disease.

Automated summary

The outbreak of COVID-19 caused by SARS-CoV-2 has led to daunting complications worldwide. Increasing studies are shedding light on new features of the virus in hopes of finding proper treatment. Activation of antiviral immune responses by SARS-CoV-2 can lead to uncontrolled inflammation in severe cases, highlighting the importance of understanding lymphocyte dysfunction and guiding clinical management strategies.