SARS-CoV-2-Specific T Cell Responses Are Stronger in Children With Multisystem Inflammatory Syndrome Compared to...

Area of Science:

• Immunology
• Virology
• Pediatrics

Background:

• Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection presents differently in adults and children.
• Children rarely develop severe acute illness but are at risk for Multisystem Inflammatory Syndrome in Children (MIS-C).
• Differences in SARS-CoV-2-specific T cell (CST) responses may explain age-related clinical presentations.

Purpose of the Study:

• To compare the magnitude and antigen specificity of CST responses between convalescent adults and children with and without MIS-C.
• To investigate the role of T cell responses in the distinct clinical outcomes of SARS-CoV-2 infection in different age groups.

Main Methods:

• Expanded CSTs from blood of convalescent children and adults post-SARS-CoV-2 infection.
• Evaluated CSTs using intracellular flow cytometry, surface markers, and cytokine production after stimulation with SARS-CoV-2 peptides.
• Measured serum/plasma antibody to spike and nucleocapsid proteins using the luciferase immunoprecipitation systems (LIPS) assay.

Main Results:

• High seropositivity for SARS-CoV-2 antibodies was observed across all groups (MIS-C patients, non-MIS-C children, adults).
• CST responses were significantly higher in MIS-C patients compared to children with uncomplicated SARS-CoV-2 infection.
• CST responses in MIS-C patients were weaker than those observed in convalescent adults.

Conclusions:

• Age-related differences in CST response magnitude suggest distinct post-infectious immunity in children versus adults.
• Children with MIS-C demonstrate an intermediate CST response profile, stronger than uncomplicated pediatric cases but weaker than adults.
• These findings highlight the complex interplay between T cell immunity and clinical outcomes in SARS-CoV-2 infection across age groups.