Relationship between Selective IgA Deficiency and COVID-19 Prognosis.

The prevalence and mortality rates of coronavirus disease 2019 (COVID-19) widely vary among populations. Mucosal immunity is the first barrier to the pathogen's entry into the body. Immunoglobulin A (IgA) is the primary antibody responsible for mucosal immunity. We explored the relationship between selective IgA deficiency (SIgAD) and COVID-19 severity. We included 424 patients (203 women) with COVID-19. Eleven patients had SIgAD. Laboratory data of patients with SIgAD and normal IgA levels were compared. The relationship between SIgAD and severe COVID-19 infection was explored using logistic regression analysis. In the univariate logistic regression analysis, the risk of severe COVID-19 disease in patients with SIgAD was approximately 7.7-fold higher than that in other patients (odds ratio [OR], 7.789; 95% confidence interval [CI], 1.665-36.690, P = 0.008), while it was 4-fold (OR, 4.053; 95% CI, 1.182-13.903, P = 0.026) higher in the multivariate logistic regression analysis. Serum IgA levels were positively correlated with total lymphocyte counts and negatively correlated with C-reactive protein levels, which was a risk factor for severe COVID-19. In patients with SIgAD, the number of severe acute respiratory coronaviruses 2 that pass through mucosal membranes may be increased, leading to complications such as cytokine storm syndrome and acute respiratory distress syndrome.

Memory B cells and serum immunoglobulins are associated with disease severity and mortality in patients with COVID-19.

PURPOSE OF THE STUDY: The aim of this study was to investigate the relationship of B cell-mediated immunity with disease severity and mortality in patients with COVID-19. STUDY DESIGN: In this retrospective cohort and single-centre study, 208 patients with laboratory-confirmed COVID-19 were recruited. A COVID-19 severity score, ranging from 0 to 10, was used to evaluate associations between various factors. Serum immunoglobulin levels and the number of cells in B lymphocyte subsets were measured and their association with disease severity and mortality in patients with COVID-19 examined. RESULTS: The median age of the patients was 50 (35-63) years and 88 (42%) were female. The number of deceased patients was 17. The median COVID-19 severity score was 8 (6-8) in deceased patients and 1 (0-2) in survivors. Deceased patients had significantly lower levels of total B lymphocytes, naive B cells, switched memory B cells, and serum IgA, IgG, IgG1 and IgG2 than recovered patients (all p<0.05). In addition, a significant negative correlation was found between the number of these parameters and COVID-19 severity scores. Decrease in the number of total B cells and switched memory B cells as well as lower serum IgA, IgG and IgG1 levels were independent risk factors for mortality in patients with COVID-19. CONCLUSION: In the present study, the prognosis of patients with COVID-19 was shown to be associated with the B cell subset and serum immunoglobulin levels.