Impaired immune responses have been hypothesised to be a possible trigger of unfavourable outcomes in coronavirus disease 2019 (COVID-19). We aimed to characterise IgM memory B cells in patients with COVID-19 admitted to an internal medicine ward in Northern Italy. Overall, 66 COVID-19 patients (mean age 74 ± 16.6 years; 29 females) were enrolled. Three patients (4.5%; 1 female) had been splenectomised and were excluded from further analyses. Fifty-five patients (87.3%) had IgM memory B cell depletion, and 18 (28.6%) died during hospitalisation (cumulative incidence rate 9.26/100 person-week; 5.8–14.7 95% CI). All patients who died had IgM memory B cell depletion. A superimposed infection was found in 6 patients (9.5%), all of them having IgM memory B cell depletion (cumulative incidence rate 3.08/100 person-week; 1.3–6.8 95% CI). At bivariable analyses, older age, sex, number of comorbidities, and peripheral blood lymphocyte count < 1500/µl were not correlated with IgM memory B cell depletion. A discrete-to-marked reduction of the B-cell compartment was also noticed in autoptic spleen specimens of two COVID-19 patients. We conclude that IgM memory B cells are commonly depleted in COVID-19 patients and this correlates with increased mortality and superimposed infections.
【저자키워드】 Adaptive immunity, Infectious diseases, Lymphocytes, Immunopathogenesis, 【초록키워드】 COVID-19, coronavirus disease, IgM, Coronavirus disease 2019, immune response, Infection, Comorbidities, memory B cells, Sex, outcome, Italy, Peripheral blood, Lymphocyte count, lymphocyte, infections, immune responses, female, Patient, Older age, incidence rate, age, hospitalisation, spleen, memory B cell, B-cell, internal medicine, COVID-19 patient, Trigger, cumulative incidence rate, reduction, 95% CI, specimen, increased mortality, cumulative, two COVID-19 patients, females, Cell, memory B, enrolled, died, analyses, Impaired, hypothesised, not correlated, number of comorbidities, patients with COVID-19, were excluded, 【제목키워드】 COVID-19, IgM, memory B cells, outcome, predict, Depletion, circulating,