Résumé
During SARS-CoV-2 infection, children are relatively spared from severe forms of COVID-19 compared to adults. Monocytes and neutrophils play important roles in the hyper-inflammatory responses characteristic of severe forms of SARS-CoV-2 infection. Materials and methods: we assessed leukocyte activation in 55 children attending the emergency department for acute fever between March 2020 and September 2021. The following markers were analyzed by flow cytometry: CD169 and HLA-DR on monocytes, CD64 and CD16 on neutrophils.Results: fifteen of the children had SARS-CoV-2 infection, 15 had bacterial infections, 15 had inflammatory diseases including 9 with multisystem inflammatory syndrome in children (MIS-C) and 6 with Kawasaki syndrome. We observed overexpression of CD169 on monocytes in all patients with a diagnosis of SARS-CoV-2, while overexpression of CD64 on neutrophils was observed with bacterial infections and MIS-C and Kawasaki syndrome. There was a decrease in the expression of HLA-DR on monocytes in the bacterial infection and inflammatory pathology groups.Conclusion: leukocyte analysis identifies distinct activation patterns in children during SARS-CoV-2 infections,bacterial infections, and MIS-C/Kawasaki syndrome.