Plasma cells linked to survival benefit in severe COVID-19

Patients with severe COVID-19 who have detectable plasma cells in the peripheral blood have better survival despite adjusting for covariates associated with disease severity, reports a study.

The researchers identified hospitalized adult patients with confirmed SARS-CoV-2 infection and stratified by presence of plasma cells and World Health Organization disease severity using the Johns Hopkins COVID-19 Precision Medicine Analytics Platform Registry. A sensitive flow cytometric screening method for highly fluorescent lymphocytes was applied to identify plasma cells, confirmed microscopically.

Finally, time to death and time to clinical improvement by the presence of plasma cells in patients with severe disease were evaluated using Cox regression models.

Plasma cells were identified in 371 of 2,301 hospitalized patients with COVID-19. Those with plasma cells were more likely to have severe disease, but 86.6 percent developed plasma cells following onset of severe disease.

After adjusting for age, sex, body mass index, race, and other covariates associated with disease severity, patients with plasma cells were found to have a lower risk of death (adjusted hazard ratio, 0.57, 95 percent confidence interval, 0.38–0.87; p=0.008).

In addition, no significant association was observed between the presence of plasma cells and time to clinical improvement.

“Further investigation is warranted to understand the role of plasma cells in the immune response to COVID-19,” the researchers said.

Cytokines in severe COVID-19 are linked to proliferation, differentiation, and survival of plasma cells. These cells are not routinely found in peripheral blood but may produce virus-neutralizing antibodies later in the course of an infection, according to the researchers.