A new study says that one type of antibody may be driving severe COVID-19 in adults, while a different type may be driving a rare but dangerous condition called multisystem inflammatory syndrome in children (MIS-C) that children with COVID-19 can develop.
Researchers at the Ragon Institute of MGH, MIT and Harvard and Massachusetts General Hospital published their results last month in Nature Medicine.
“We noticed children who developed MIS-C after COVID disease or exposure had high levels of a specific type of antibody called IgG,” Dr. Lael Yonker, a pediatric pulmonologist at MGH and assistant professor at Harvard Medical School, said in a statement last month from the institute.
“Normally, IgG acts to control an infection, but with MIS-C, the IgG is triggering activation of immune cells, which may be driving the severe illness seen in MIS-C,” Yonker said.
In the case of adults with severe COVID-19, researchers said, increased levels of different antibodies, IgA antibodies, could be the problem.
Those antibodies interact with a type of immune cells called neutrophils and cause the neutrophils to release cytokines, Galit Alter, a core member of the Ragon Institute, said in the statement.
Yannic Bartsch, the study’s first author and a research fellow at the institute, said in the statement, “In adults with severe COVID-19, high levels of IgA antibodies could be driving neutrophils to release too many cytokines, with the potential of causing a cytokine storm.”
The study said the “unpredictable nature” of the severity of disease is “alarming.”
And it suggested ”in the absence of therapeutics able to reverse these clinical manifestations, understanding the immunological mechanisms that underlie these unusual complications of [coronavirus] infection might provide critical insights for the design and delivery of therapeutics for these unique populations.”
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