Clinical assessment of children with long COVID syndrome.

BACKGROUND: There is a need for further understanding pediatric long COVID syndrome (LCS) to be able to create specific case definitions and guidelines for providing good clinical care. METHODS: Medical records of all LCS patients who presented at our designated LC clinic were collected. We carried out descriptive analyses summarizing the history, clinical presentation, and findings of children, while doing a diagnosis of exclusion with multi-disciplinary medical examinations (physical, laboratory, and radiological examinations, specialist consultations, etc.) without a control group. RESULTS: Most children reported at least minor impairment to their quality of life, of which 17 (23%) had moderate or severe difficulties. Findings that could be directly connected to the linked complaint category were observed in an average of 18%, respiratory symptoms with objective alterations being the most frequent (37%). Despite our detecting mostly non-specific conditions, in a smaller number we identified well-described causes such as autoimmune thyroiditis (7%). CONCLUSIONS: The majority of children stated an impairment in their quality of life, while symptom-related conditions were detected only in a minority. Controlled studies are needed to separate the effect of the pandemic era from the infection itself. Evidence-based pediatric guidelines could aid to rationalize the list of recommended examinations. IMPACT: Long COVID syndrome is a complex entity with a great impact on children's everyday lives. Still, there is no clear guidance for pediatric clinical management. Systematic, detailed studies with medical assessment findings could aid the process of creating evidence-based guidelines. We present validated systematic information collected during in-person medical assessments with detailed medical findings and quality of life changes. While making a diagnosis of exclusion, we could confirm symptom-related conditions only in a minority of children; however, the majority reported at least minor impairment to their quality of life.

Recognition of new citrulline-containing peptide epitopes by autoantibodies produced in vivo and in vitro by B cells of rheumatoid arthritis patients.

Anti-citrullinated peptide/protein antibodies (ACPAs) are highly sensitive and specific markers of rheumatoid arthritis (RA). Identification of peptide epitopes that may detect different subgroups of RA patients might have diagnostic and prognostic significance. We have investigated citrulline- and arginine-containing peptide pairs derived from filaggrin, collagen or vimentin, and compared this citrulline-peptide panel with the serological assays conventionally used to detect ACPAs. Furthermore, we studied if the same citrulline-peptides identify antibody-secreting cells in in vitro cultures of RA B cells. Recognition of citrulline- and arginine-containing filaggrin, vimentin and collagen peptide epitopes were tested by Multipin ELISA system, by indirect ELISA and by a peptide-specific microarray. B cells were purified from blood by negative selection; antibody-producing cells were enumerated by ELISPOT assay. The panel composed of citrulline-peptide epitopes of filaggrin, collagen and vimentin was recognized by RA sera with a sensitivity and specificity comparable with the currently used tests. Moreover, the combined citrulline-peptide panel including the new short epitope peptide of filaggrin, fil311-315, also identified nearly one-third of RA cases that were negative for antibodies against cyclic citrullinated peptides, mutated citrullinated vimentin or for rheumatoid factor. The results with the peptide-specific microarray have shown that although most ACPAs recognizing the four citrulline peptides are IgG, some of them specifically recognizing citrulline-containing filaggrin peptides (fil311-315 and fil306-326) are IgM, and so may be produced either by newly formed activated B cells or by unswitched B memory cells. Furthermore, the citrulline-peptides of filaggrin and vimentin detect ACPA-producing cells, and so could also be applied to study the B cells of RA patients.