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Objective. This study was undertaken to determine whether BAFF blockade can be used to prevent or treat antiphospholipid syndrome in a mouse model.Methods. Eight-and 12-week-old (NZW ؋ BXSB)F 1 mice were treated with BAFF-R-Ig or TACI-Ig alone or in addition to a short course of CTLA-4Ig. Mice were monitored for thrombocytopenia and proteinuria. Sera were tested for anticardiolipin antibodies (aCL), BAFF levels, and levels of soluble vascular cell adhesion molecule and E-selectin. Mice were killed at 17, 22, or 32 weeks of age, and kidneys and hearts were subjected to histologic examination. Spleen cells were phenotyped and enzyme-linked immunospot assays for autoantibody-producing B cells were performed.Results. Both BAFF-R-Ig and TACI-Ig prevented disease onset and significantly prolonged survival. Treated mice had significantly smaller spleens than controls, with fewer B cells and fewer activated and memory T cells. BAFF blockade did not prevent the development of aCL, and there was only a modest delay in the development of thrombocytopenia. However, treated mice had significantly less nephritis and myocardial infarcts than did controls.Conclusion. Our findings suggest that aCL are generated in the germinal center, which is relatively independent of BAFF. Effector function of antiplatelet antibodies was only modestly affected by BAFF blockade. In contrast, myocardial infarctions were prevented, suggesting that triggering of thromboses requires both autoantibodies and mediators of inflammation. Similarly, renal damage requires both immune complexes and effector cells. The dissociation between autoantibody production and inflammation that may occur with B cell-depleting therapies underscores the role of B cells as effector cells in the autoimmune response.

Recent reports have described a secondary Multisystem Inflammatory Syndrome in Children (MIS-C) after a prior COVID-19 infection that often has features of Kawasaki disease (KD). Here, we report the case of a 36-year-old woman who presented to the emergency department hypotensive and tachycardic after 1 week of fevers, abdominal pain, vomiting and diarrhea, and was found to have the classic phenotype of complete Kawasaki's Disease including nonexudative conjunctivitis, cracked lips, edema of the hands and feet, palmar erythema, a diffuse maculopapular rash, and cervical lymphadenopathy. Initial laboratory studies were significant for hyponatremia, elevated liver function tests including direct hyperbilirubinemia, and leukocytosis with neutrophilia. Imaging revealed mild gallbladder wall edema, a small area of colitis, and small pleural effusion. She was treated for Kawasaki Disease Shock Syndrome (KDSS) with pulse dose solumedrol, IVIG, and aspirin with near resolution of symptoms and normalization of vital signs within 1 day and subsequent improvement in her laboratory abnormalities. She was later found to be COVID-19 IgG positive, suggesting past exposure. This case represents an early report of a KD-like illness in an adult with serologic evidence of a previous COVID-19 infection, similar to MIS-C. It suggests that the virulent strain of SARS-CoV-2 appears to cause a post-infectious inflammatory syndrome similar to KD in adults, as well as children. Our understanding of the myriad of COVID-19 symptoms and sequelae is rapidly evolving. We recommend physicians remain vigilant for inflammatory syndromes that mimic KD/KDSS which may warrant prompt treatment with IVIG and steroids.

IMPORTANCETo date, no study has characterized the mucocutaneous features seen in hospitalized children with multisystem inflammatory syndrome in children (MIS-C) or the temporal association of these findings with the onset of systemic symptoms. OBJECTIVE To describe the mucocutaneous findings seen in children with MIS-C during the height of the coronavirus disease 2019 (COVID-19) pandemic in New York City in 2020. DESIGN, SETTING, AND PARTICIPANTS A retrospective case series was conducted of 35 children admitted to 2 hospitals in New York City between April 1 and July 14, 2020, who met Centers for Disease Control and Prevention and/or epidemiologic criteria for MIS-C. MAIN OUTCOMES AND MEASURES Laboratory and clinical characteristics, with emphasis on mucocutaneous findings, of children who met criteria for MIS-C. The characterization of mucocutaneous features was verified by 2 board-certified pediatric dermatologists. RESULTS Twenty-five children (11 girls [44%]; median age, 3 years [range, 0.7-17 years]) were identified who met definitional criteria for MIS-C; an additional 10 children (5 girls [50%]; median age, 1.7 years [range, 0.2-15 years]) were included as probable MIS-C cases (patients met all criteria with the exception of laboratory test evidence of severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] infection or known exposure). The results of polymerase chain reaction tests for SARS-CoV-2 were positive for 10 patients (29%), and the results of SARS-CoV-2 immunoglobulin G tests were positive for 19 patients (54%). Of the 35 patients, 29 (83%) exhibited mucocutaneous changes, with conjunctival injection (n = 21), palmoplantar erythema (n = 18), lip hyperemia (n = 17), periorbital erythema and edema (n = 7), strawberry tongue (n = 8), and malar erythema (n = 6) being the most common findings. Recognition of mucocutaneous findings occurred a mean of 2.7 days (range, 1-7 days) after the onset of fever. The duration of mucocutaneous findings varied from hours to days (median duration, 5 days [range, 0-11 days]). Neither the presence nor absence of mucocutaneous findings was significantly associated with overall disease severity. CONCLUSIONS AND RELEVANCEIn this case series of hospitalized children with suspected MIS-C during the COVID-19 pandemic, a wide spectrum of mucocutaneous findings was identified. Despite their protean and transient nature, these mucocutaneous features serve as important clues in the recognition of MIS-C.