Polyclonal expansion of TCR Vbeta 21.3+ CD4+ and CD8+ T cells is a hallmark of Multisystem Inflammatory Syndrome in Children.

Multiple Inflammatory Syndrome in Children (MIS-C) is a delayed and severe complication of SARS-CoV-2 infection that strikes previously healthy children. As MIS-C combines clinical features of Kawasaki disease and Toxic Shock Syndrome (TSS), we aimed to compare the immunological profile of pediatric patients with these different conditions. We analyzed blood cytokine expression, and the T cell repertoire and phenotype in 36 MIS-C cases, which were compared to 16 KD, 58 TSS, and 42 COVID-19 cases. We observed an increase of serum inflammatory cytokines (IL-6, IL-10, IL-18, TNF-α, IFNγ, CD25s, MCP1, IL-1RA) in MIS-C, TSS and KD, contrasting with low expression of HLA-DR in monocytes. We detected a specific expansion of activated T cells expressing the Vß21.3 T cell receptor ß chain variable region in both CD4 and CD8 subsets in 75% of MIS-C patients and not in any patient with TSS, KD, or acute COVID-19; this correlated with the cytokine storm detected. The T cell repertoire returned to baseline within weeks after MIS-C resolution. Vß21.3+ T cells from MIS-C patients expressed high levels of HLA-DR, CD38 and CX3CR1 but had weak responses to SARS-CoV-2 peptides in vitro. Consistently, the T cell expansion was not associated with specific classical HLA alleles. Thus, our data suggested that MIS-C is characterized by a polyclonal Vß21.3 T cell expansion not directed against SARS-CoV-2 antigenic peptides, which is not seen in KD, TSS and acute COVID-19.

Efficacy and Tolerance of Lidocaine 5% Patches in Neuropathic Pain and Pain Related to Vaso-occlusive Sickle Cell Crises in Children: A Prospective Multicenter Clinical Study.

BACKGROUND: The management of neuropathic pain and pain related to bone vaso-occlusive crises in sickle cell disease remains challenging in children. Lidocaine 5% patches are recommended in adults for neuropathic pain treatment, but they are not recommended in children. The purpose of this study was to assess the efficacy and tolerance of lidocaine 5% patches in pediatric inpatients. METHODS: This prospective, multicenter, single-arm, phase II study aimed to assess the use of lidocaine 5% patches in 6- to 21-year-old pediatric patients suffering from neuropathic pain or superficial bone vaso-occlusive crises. Patches were applied on the painful area for 12 hours a day. The primary endpoint was the proportion of inpatients with significant pain relief defined as a decrease of at least 2 points on the visual analog pain scale (VAS) measured at 12 hours after patch placement over at least 2 consecutive days. RESULTS: The 12-hour VAS score decreased by at least 2 points over 2 consecutive days in 48.6% of patients 95% unilateral confidence interval (33.8%). Only 7.7% of patients experienced grade 1 or grade 2 toxicities. CONCLUSION: Although lidocaine 5% patches decreased the pain's intensity in nearly half of the enrolled patients with an excellent tolerance, the efficacy endpoint was not reached. Further studies should consider a more refined selection of the experimental population to assess the efficacy of lidocaine 5% patches in the pediatric population.

Newly diagnosed immune thrombocytopenic purpura in childhood: successful implementation of a limited intervention strategy in the setting of pediatric emergency care.

Immune thrombocytopenic purpura is a bleeding disorder for which management remains mainly guided by platelet counts. Pediatric hematologists and emergency physicians collaborated to set up a limited intervention strategy, focusing on clinical bleeding severity irrespective of platelet counts, starting in the emergency room. We report how this strategy was safely applied for 106 consecutive children admitted for newly diagnosed immune thrombocytopenic purpura.