An association between immune status and chest CT scores in COVID-19 patients.

BACKGROUND: The characteristic features of the immune responses of COVID-19 patients and how they reflect lung involvement have not been clearly elucidated. AIM: The aim of this study was to examine the immune status and the correlations thereof with chest CT scores and lung involvement of patients with COVID-19. METHODS: In this retrospective and single-center study, 72 patients with laboratory-confirmed COVID-19 were recruited. The counts of peripheral lymphocyte subsets (CD3+ T cells, CD4+ T cells, CD8+ T cells, CD19+ B cells and CD16+ 56+ NK cells) and those of serum immunoglobulins (IgA, IgG, IgM) were measured and their associations with chest CT scores analysed. RESULTS: The proportions of lymphopenia in patients with extensive lung involvement were twice that in the general study population. In the severe disease group, the levels of total lymphocytes, T cells, B cells, NK cells; and serum IgA levels, were significantly lower than in the mild disease group (all P < .05). We found that the numbers of lymphocyte subsets and the IgA level negatively correlated with the chest CT scores. On multivariate regression analysis, pretreatment decreases in total lymphocytes, CD3+ T cells, CD4+ T cells, and CD19+ B cells, and serum IgA levels, were independent predictors of severe lung involvement. CONCLUSIONS: The cell numbers of peripheral lymphocyte subsets and the serum IgA level were negatively correlated with the chest CT scores in COVID-19 patients. These parameters tended to independently predict severe lung involvement in such patients.