Specific types of antibodies drive Covid-19 outcomes, study finds

Prashasti Awasthi Mumbai | Updated on February 19, 2021

Symptoms of novel coronavirus vary from person to person on the basis of age, gender, co-morbidities, among other factors.

Hence, a new study aims to find out why Covid-19 can lead to such distinctly different outcomes in different populations.

The study, published in the journal Nature Medicine, detected specific types of antibodies that may be driving these different responses. This includes one specific to severe disease in adults and another specific to MIS-C in children.

“We noticed children who developed MIS-C after Covid disease or exposure had high levels of a specific type of antibody called IgG,” said one of the authors Lael Yonker, MD, director of the Massachusetts General Hospital Cystic Fibrosis Center.

He added, “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 further explained that specifically, IgG antibodies interact with cells called macrophages, which live throughout the body’s tissues. If there are too many IgG bodies activating these macrophages, this could cause inflammation in many different organs and systems, which is seen in MIS-C.

These high levels of IgG antibodies were only found in children who developed MIS-C after contracting or being exposed to Covid-19.

The researchers used unique “systems serology” technology to carefully perform a detailed comparison of the immune responses in children –17 with MIS-C and 25 with mild Covid-19 – to the responses of 26 adults with severe disease and 34 adults with mild disease.

The researchers noted in the study that for adults with severe Covid-19, they saw increased levels of IgA antibodies, which interact with a type of immune cells called neutrophils and cause the neutrophils to release cytokines.

If there are too many IgA antibodies, the neutrophils may be pushed to release too many cytokines, which could contribute to a cytokine storm, one of the symptoms of severe Covid-19, the study stated.

In both cases, the study shows, it may be a high level of a specific type of antibody causing the disease severity.

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Published on February 19, 2021
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