Children with MIS-C mount normal T-cell response to SARS-CoV-2, study finds

Children with an inflammatory syndrome linked to SARS-CoV-2 infection mount a normal T-cell response to the virus, according results from a multi-institutional study reported in the European Journal of Immunology.

Researchers had hypothesized that multisystem inflammatory syndrome in children (MIS-C) may result from an abnormal T-cell response against the virus, leading to inflammation.

Alessandra Franco, MD, PhD, an associate professor of pediatrics at the University of California San Diego School of Medicine, is a T-cell biologist and immunologist whose past work involved studying the cells’ effect on cancer.

“We're still in the process of understanding a lot of aspects of the disease,” Franco told Healio. “But the critical question, at least for me, was how these children respond to the virus. Do they respond at all? Because some are very young, although the cohorts usually are a little older than what we see with Kawasaki disease.”

For the study, Franco collaborated with Jane Burns, MD of the Rady Children’s Hospital in San Diego, and others. Burns’ research specializes in Kawasaki disease, the symptoms of which bear a resemblance to those of MIS-C.

The team compared responses from 11 children with MIS-C with the responses of participants in two control groups — one comprising two children and five adults who had recovered from previous SARS-CoV-2 infections without MIS-C, and another comprising 10 children with Kawasaki disease.

“We took the cells from the children, we stimulated the cells in vitro with the peptide, and then we measured the activation state of the cells,” Franco said.

Nine of the 11 patients with MIS-C had T cells that recognized SARS-CoV-2, but the responses did not correlate with disease severity or age, and instead acted similarly to those of the children and adults who had a previous SARS-CoV-2 infection but not MIS-C.

What researchers did find was that these patients had lower numbers of tolerogenic myeloid dendritic cells — a different kind of immune cell that prevents inflammation — compared with t their peers without MIS-C.

Franco said the team plans to examine how T cells in children with MIS-C assist in returning their immune systems to normal through their recovery, as well as dynamics in children who are vaccinated and not vaccinated.

“[This wasn’t mentioned in the paper, but] in my opinion, the best way to prevent MIS-C [as of now] is that the parents need to be vaccinated,” Franco said.

She added that pediatricians should take care to recognize MIS-C in their patients.

“What is very important for physicians is to make the diagnosis because, again, the disease shows different symptoms and it is very similar to Kawasaki disease in the clinic but it's completely different as far as immunopathology,” Franco said. “Many children did not have acute symptoms of SARS-COV-2, so the disease arises weeks after the infection. The awareness would be the most important aspect as far as diagnosis.”

Reference:

Kids with MIS-C mount normal T cell response to COVID-19. https://www.eurekalert.org/news-releases/930914. Published Oct. 7, 2021. Accessed Oct. 12, 2021.