Clinical and immunological features of severe and moderate coronavirus disease 2019

BACKGROUND. Since December 2019, an outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in Wuhan, and is now becoming a global threat. We aimed to delineate and compare the immunological features of severe and moderate COVID-19. METHODS. In this retrospective study, the clinical and immunological characteristics of 21 patients (17 male and 4 female) with COVID-19 were analyzed. These patients were classified as severe (11 cases) and moderate (10 cases) according to the guidelines released by the National Health Commission of China. RESULTS. The median age of severe and moderate cases was 61.0 and 52.0 years, respectively. Common clinical manifestations included fever, cough, and fatigue. Compared with moderate cases, severe cases more frequently had dyspnea, lymphopenia, and hypoalbuminemia, with higher levels of alanine aminotransferase, lactate dehydrogenase, C-reactive protein, ferritin, and D-dimer as well as markedly higher levels of IL-2R, IL-6, IL-10, and TNF-alpha. Absolute numbers of T lymphocytes, CD4(+) T cells, and CD8(+) T cells decreased in nearly all the patients, and were markedly lower in severe cases (294.0, 177.5, and 89.0 x 10(6)/L, respectively) than moderate cases (640.5, 381.5, and 254.0 x 10(6)/L, respectively). The expression of IFN-gamma by CD4(+) T cells tended to be lower in severe cases (14.1%) than in moderate cases (22.8%). CONCLUSION. The SARS-CoV-2 infection may affect primarily T lymphocytes, particularly CD4(+) and CD8(+) T cells, resulting in a decrease in numbers as well as IFN-gamma production by CD4(+) T cells. These potential immunological markers may be of importance because of their correlation with disease severity in COVID-19.