Background The immune response plays a pivotal role in dictating the clinical outcome in severe acute respiratory syndrome coronavirus 2 (SARS – CoV – 2)-infected adults, but it is still poorly investigated in the pediatric population. Methods Of 209 enrolled subjects, 155 patients were confirmed by PCR and/or serology as having coronavirus disease 2019 (COVID-19). Blood samples were obtained at a median of 2.8 (interquartile, 2.1–3.7) and 6.1 (5.3–7.2) months after baseline (symptom onset and/or first positive virus detection). The immune profiles of activation, senescence, exhaustion, and regulatory cells were analyzed by flow cytometry. Neutralizing antibodies (nAbs) were detected by a plaque reduction neutralization test. In available nasopharyngeal swabs at baseline, SARS-CoV-2 levels were quantified by digital droplet PCR (ddPCR). Results Overall, COVID-19 patients had higher levels of immune activation, exhaustion, and regulatory cells compared to non-COVID-19 subjects. Within the COVID-19 group, activated and senescent cells were higher in adults than in children and inversely correlated with the nAbs levels. Conversely, Tregs and Bregs regulatory cells were higher in COVID-19 children compared to adults and positively correlated with nAbs. Higher immune activation still persisted in adults after 6 months of infection, while children maintained higher levels of regulatory cells. SARS-CoV-2 levels did not differ among age classes. Conclusions Adults displayed higher immune activation and lower production of anti-SARS-CoV-2 nAbs than children. The different immune response was not related to different viral load. The higher expression of regulatory cells in children may contribute to reduce the immune activation, thus leading to a greater specific response against the virus.
【저자키워드】 senescence, COVID-19 children, immune activation, Tregs and Bregs, neutralizing antibodies (NAbs), 【초록키워드】 COVID-19, coronavirus disease, SARS-CoV-2, Coronavirus disease 2019, coronavirus, immune response, Neutralizing antibodies, serology, antibody, pediatric, children, Infection, Immune profile, senescence, severe acute respiratory syndrome Coronavirus, virus, anti-SARS-CoV-2, flow cytometry, Clinical outcome, Nasopharyngeal swab, Adults, Viral, PCR, Plaque reduction neutralization test, Viral load, immune activation, nasopharyngeal swabs, neutralization test, Patient, virus detection, Exhaustion, CoV, age, respiratory, expression, Treg, COVID-19 patients, NAb, COVID-19 patient, Tregs, symptom onset, Non-COVID-19, acute respiratory syndrome, Activation, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, Blood samples, NAbs, blood sample, COVID-19 group, plaque reduction neutralization, regulatory cells, first positive, Result, greater, enrolled, not differ, analyzed, investigated, median, activated, subjects, contribute, correlated, reduce, quantified, baseline, Breg, interquartile, positively correlated, regulatory cell, senescent cell, 【제목키워드】 SARS-CoV-2, Specific, Lower,