Depletion of circulating IgM memory B cells predicts unfavourable outcome in COVID-19

Abstract

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.

Implications of SARS‐CoV‐2 infection for neurogastroenterology

“…In particular, spleen atrophy, mainly affecting the white pulp, was observed in post‐mortem cases of COVID‐19 120 . A study exploring spleen function in 66 COVID‐19 patients admitted to an internal medicine ward found a high prevalence of IgM memory B‐cell depletion, and this was associated with greater mortality and development of superimposed bacterial infections 121 . However, more data are still needed in order to ascertain the role of SARS‐CoV‐2 in causing direct liver damage, pancreatic, and splenic involvement.…”

Risk factors associated with severe outcomes of COVID-19: A systematic rapid review to inform national guidance on vaccine prioritization in Canada

“…Finally, there are some rare conditions (e.g., thalassemia, splenic dysfunction) for which to our knowledge, no large and well-adjusted studies have been published. In these cases, governing bodies may need to rely on evidence available for other infectious diseases, or from smaller cohorts suggesting the potential for increased risk [18,[133][134][135][136].…”

Interleukin-7 Reverses Lymphopenia and Improves T-Cell Function in Coronavirus Disease 2019 Patient With Inborn Error of Toll-Like Receptor 3: A Case Report

“…The patient described in this report maintained a robust anti–SARS-CoV-2 antibody response from day 5 post admission to day 21. Although some reports describe weak early antibody production to correlate with severity of disease ( 31 ), others describe no correlation between antibody levels and severity of disease, with a trend toward higher levels in more severe patients ( 32 ). Antibody levels are unlikely to be positively predictive of outcomes, and therefore, immunotherapy to stimulate the T-cell adaptive response should be considered.…”