Abnormal T cell responses to SARS-CoV-2 do not appear to be a cause of multisystem inflammatory syndrome in children with MIS-C, researchers from the University of California San Diego School of Medicine report in a study in European Journal of Immunology, according to a news release.
(MIS-C) is a serious condition associated with a recent COVID-19 infection. The syndrome is rare, and it remains unclear how the viral infection leads to MIS-C and why it only develops in some children.
The researchers set out to explore the hypothesis that children with MIS-C might mount an abnormal T cell response — immune cells that help the body fight viral infections — to the coronavirus, causing inflammation, the university said.
However, all children with MIS-C who participated had normal T cell responses to the COVID-19 virus, comparable to children and adults who had recovered from COVID-19 without MIS-C. Children with a clinically similar but unrelated inflammatory condition called Kawasaki disease also served as a control group.
The team compared responses to bits of the COVID-19 virus by T cells isolated from 11 children with MIS-C to two control groups: 1) two children and five adults who had recovered from previous COVID-19 infections without MIS-C and 2) 10 children with Kawasaki disease.
They found that nine of the 11 children with MIS-C had T cells that specifically recognized the COVID-19 virus. But these T cell responses did not correlate with disease severity or age. Their T cells acted similarly to those of children and adults who had a previous COVID-19 infection but not MIS-C.
Examining additional children with MIS-C, the team found that these patients did have lower numbers of other immune cells, such as tolerogenic myeloid dendritic cells, compared to the children without MIS-C. These cells reduce inflammation and are particularly numerous in children. Fewer of these cells might help contribute to the development of MIS-C.
