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Background: People with HIV (PWH) on antiretroviral therapy (ART) appear to be at higher risk for worse COVID-19 outcomes, but the underlying mechanisms-including effects of COVID-19 and host factors on the broader humoral immune repertoire-are poorly understood. Method(s): REPRIEVE enrolled a global cohort of ART-treated PWH ages 40-75. COVID+ was defined by positive receptor binding domain IgG or IgA from annual visits 5/2020-2/2021. Antibody isotype, subclass, and Fc receptor Luminex arrays to SARS-CoV-2, CMV, EBV, HSV, HIV, influenza, pneumococcus, and RSV were assessed. Report of COVID diagnosis (collected every 4 months) was defined as mild, moderate, or severe (asymptomatic if no clinical diagnosis but IgG/ IgA+). FDR-corrected regression was used to assess effects of 1) COVID+ on non- SARS-CoV-2 repertoire in full cohort and 2) host factors on non-SARS-CoV-2 and SARS-CoV-2 repertoire in COVID- and COVID+ cohorts, respectively, adjusted for age, sex, region, nadir CD4, and HIV VL at entry. Result(s): Of 2,464 unvaccinated participants, 283 (11%) were COVID+;260 (92%) were asymptomatic. Median age was 53, 35% were women, 50% had nadir CD4 < 200, median current CD4 was 649, and 97% had HIV VL < 400. In the full cohort, COVID+ was associated with higher CMV PP65 IgG3 and FcgammaRIIA (P< 0.05);COVID severity was not associated with the non-SARS-CoV-2 repertoire. Among COVID-, older age, female sex, and lower nadir CD4 were associated with higher EBV and CMV responses;IgG1 levels were higher in women for all non-SARS-CoV-2 antigens assessed (P< 0.05). Among COVID+, higher BMI was associated with amplified SARS-CoV-2 IgG, IgA, IgM, and FcgammaRIIA responses (P< 0.05). Lower nadir CD4 was associated with a SARSCoV- 2 repertoire shift toward IgM and FcgammaRIIB (P< 0.05). Age and sex were not associated with SARS-CoV-2-related repertoire changes in COVID+. Conclusion(s): Our analysis presents a comprehensive view of host factors associated with the humoral immune repertoire among a global cohort of ART-treated PWH. COVID's association with higher CMV responses may suggest increased susceptibility to or a consequence of persistent inflammation after infection. The striking amplification of SARS-CoV-2 responses with higher BMI suggests an excessive inflammatory response. Lower nadir CD4 was related to uncontrolled extra-follicular and inhibitory SARS-CoV-2 responses, which are unlikely to be protective. These findings may suggest mechanisms underlying factors associated with worse COVID-19 outcomes among PWH. (Figure Presented).
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Background and aims: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare syndrome of unclear aetiology occurring after vaccinations against COVID-19. The aim of this study was to investigate the DNA vaccine-encoded Sars-cov-2 soluble spike protein (SP) as a potential trigger of platelet activation in VITT. Methods: We studied three VITT patients and seven healthy controls (HCs) within 3 weeks from the first dose of ChAdOx1 nCoV-19. Serum levels of SP, soluble angiotensin-converting enzyme 2 (sACE2), and platelet response to VITT serum stimulation were studied. A thrombus retrieved from middle cerebral artery during mechanical thrombectomy of one VITT patient, was analysed by immunohistochemistry for SP and ACE2. Neutrophil extracellular traps (NETs) markers and coagulation parameters were also measured. Results: We detected SP and sACE2 in all VITT patients, and in two and three out of 7 HCs, respectively. VITT sera markedly activated platelets and this activation was inhibited by both anti-SP and anti-FcγRIIA blocking antibodies. The retrieved thrombus showed positive immunohistochemical labelling of platelets using an anti-SP antibody with reduced ACE2 expression, compared to a thrombus from a pre-pandemic stroke patient. Markers of endothelial dysfunction, NETs and hypercoagulability state were present in VITT sera. Conclusions: The present data provide first evidence that DNA vaccineencoded Sars-cov-2 SP is detectable in VITT sera (up to several weeks post-vaccination) and in a platelet-rich thrombus, and suggest that SP may contribute to the initial platelet stimulation in VITT patients. Anti-PF4/ polyanion antibodies development could represent an epiphenomenon, which amplifies platelet aggregation, NETosis, and coagulation cascade.
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Background: Vaccines have been an important strategy to control the SARS-CoV-2 pandemic. In The Netherlands two mRNA vaccines (BTN162b2, Pfizer-BioNTech;mRNA-1273, Moderna), and two adenovirus vector-based vaccines (ChAdOx1 nCoV-19, AstraZeneca;Ad26. COV2.S, Johnson & Johnson/Janssen) have been administered. In 2021, vaccination with the ChAdOx1 nCoV-19 was ceased in The Netherlands and other European countries due to the occurrence of thrombocytopenia and thromboembolic events. This new phenomenon was termed vaccine-induced thrombotic thrombocytopenia (VITT) and was clinically associated with thrombocytopenia and thrombosis at unusual sites, in particular cerebral venous sinus thrombosis (CVST). In addition, VITT was characterized by the presence of IgG-antibodies directed against platelet factor 4 (PF4). As PF4 appears to play a central role in the pathophysiology of VITT, it is recommended that the role of PF4 should be taken into account for VITT diagnostic testing. Aims: To characterize and define the patient population of clinically suspected VITT cases in The Netherlands from a diagnostics perspective. Methods: We describe a cohort of 283 clinically suspected VITT patients. We assessed these patients based on their clinical presentation and using an anti-PF4 IgG ELISA and a functional PF4-dependent platelet activation assay. Results: We found that when the 283 clinically suspected VITT patients were analysed in the anti-PF4 IgG ELISA: 24 (8.5%) tested positive, 248 (87.6%) tested negative, and 11 (3.9%) tested weak positive. Out of the 24 patients that tested positive in the anti-PF4 IgG ELISA, 19 (79.2%) patients also demonstrated increased PF4-dependent platelet activation. Furthermore, we observed that platelet activation was inhibited by excess levels of heparin and by a FcγRIIa-blocking antibody, indicating a role for platelet-FcγRIIa in the pathophysiology of VITT. Remarkably, we found that patients vaccinated with mRNA vaccines BTN162b2 (N = 84) and mRNA-1273 (N = 36), did not test positive in the anti-PF4 IgG ELISA. Based on these test results 19 patients (11 women) were eventually diagnosed with probable VITT, of which 13 presented with both thrombocytopenia and thrombosis and three suffered from CVST. Strikingly, discrepancies in test results were also present, including nine patients with low levels of anti-PF4 IgG but with increased PF4-dependent platelet activation, and two patients with high levels of anti-PF4 IgG but without any PF4-dependent platelet activation. Summary/Conclusions: VITT is a rare but serious complication of SARS-CoV-2 virus vaccination, particularly due to adenovirus vectorbased vaccines. Our results underline the importance of using the clinical presentation, in combination with the anti-PF4 IgG ELISA and the PF4-dependent platelet activation assay for VITT diagnostics. Discrepancies in test results, however, proved it difficult to unequivocally diagnose VITT. Therefore, it will be essential to obtain more insights into the pathophysiology of VITT in order to improve the diagnostic accuracy and identify preventive and therapeutic approaches.
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BACKGROUND: Cytokine storm in COVID-19 patients has contributed to many morbidities and mortalities in patients. Studies have found that toll-like receptors (TLRs) and some Fc receptors play essential roles in the hyperactivation of the immune system. Up to date, researchers are still in progress to discover effective and safe drugs to alleviate the hyperinflammatory state in COVID-19. The previous studies had shown that Carthamus tinctorius and its bioactive compounds might have anti-inflammatory activities in animal models. AIM: We aimed to investigate the possible interactions of several flavonoids from C. tinctorius with several immune system components using a biocomputational approach. METHODS: Molecular docking was done using the AutoDock program based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) COVID-19 pathway. The most suitable receptors found were studied to study the interactions with several flavonoids from C. tinctorius. RESULTS: TLR4, TLR8, and FcγRIIa were found to bind with SARS CoV2 inflammatory pathway and further selected as macromolecules for potential interactions study with 22 flavonoids from C. tinctorius. Of the 22 flavonoids studied, daphnoretin showed the best binding affinity with TLR4 and Rutin was shown to attach best with FcγRIIa. Unlike its excellent binding to TLR4, daphnoretin showed weak binding to TLR8. CONCLUSION: Daphnoretin showed an excellent affinity with TLR4 and might be a good candidate as an inhibitor in hyperinflammatory reactions in COVID-19 DTLR8.
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BACKGROUND: Multiple myeloma (MM) and Waldenström macroglobulinemia (WM) are associated with significant immunoparesis. Based on the ongoing COVID-19 pandemic, there is an urgent need to understand whether patients are able to mount a sufficient response to COVID-19 vaccines. METHODS: MM and WM patients are vaccinated with mRNA-1273 (Moderna), BNT162b2 mRNA (Pfizer/BioNTech), or JNJ-78436735 (Johnson & Johnson) in a prospective clinical trial. Primary endpoint is SARS-CoV-2 spike protein (S) antibody (Ab) detection 28 days after final vaccination. Secondary endpoints include functional serologic assessments and T-cell responses at 28 days, 6 months, 9 months, and 12 months following vaccination. S Abs were detected by Elecsys assay (Roche Diagnostics), with 3 0.80 U/mL defined as positive and titers > 250 U/mL considered stronger correlates of neutralization. SARS-CoV-2 wildtype and variant S-specific Ab isotypes and FcγR binding profiles were quantified by custom Luminex assay. Antibody-dependent neutrophil and cellular phagocytosis (ADNP and ADCP) were assessed using flow cytometry. RESULTS: To date 141 patients have been enrolled, 137 (91 MM and 46 WM) of whom had an S Ab assessment. Median Ab titer was 178.0 (IQR, 16.10-1166.0) for MM and 3.92 (IQR, 0-278.9) for WM. S Ab response rate was 91% (83/91) in MM and 56% (27/46) in WM. However, responses achieving S Ab >250 U/mL were 47.3% (43/91) in MM and 26.1% (12/46) in WM. In patients 375 years, responses >250 u/mL were 13.3% (2/15;p<0.05). Vaccine-specific S Ab responses >250 u/mL following mRNA-1273, BNT162b2, and JNJ-78436735 were 67.6% (23/34;p<0.05), 38.3% (18/47;p=NS), and 20% (2/10;p=NS) in MM and 50.0% (8/16;p<0.05), 14.8% (4/27;p<0.05), and 0% (0/3;p=NS) in WM. Among MM patients with progressive disease, S Ab response >250 u/mL occurred in 30% (6/20) as opposed to 55.6% (30/54) for VGPR+ (p<0.05). MM patients having autologous stem cell transplant within 12 months demonstrated 100% (5/5;p<0.05) S Ab responses. For MM patients actively receiving an anti-CD38 monoclonal Ab or an immunomodulatory drug, S Ab response occurred in 38.9% (14/36;p=NS) and 50.9% (28/55;p<0.05). Among WM patients, S Ab responses >250 U/mL occurred in 63.6% (7/11;p<0.05) previously untreated;0% (0/9;p<0.05) who received rituximab within 12 months;10% (2/20);p<0.05) on an active Bruton Tyrosine Kinase (BTK) inhibitor;and 20% (3/15;p=NS) who received other therapies. Functional Ab studies were performed on 14 MM patients, 14 WM, patients, and 14 healthy donors (HD) (Figure 1). All patients were assessed 28 days following their final vaccination and myeloma patients had an additional assessment 28 days following initial vaccination. MM and WM patients demonstrated less IGG1 and IGG3 S Ab production than HD. MM patients showed increased IgA and IgM S Ab production as well as increased FcgR2A binding following a second vaccine in contrast to HD. Both ADNP and ADCP were reduced in MM and WM patients. MM patients demonstrated improved ADCP in SARS-CoV-2 variants B.1.351, B.1.117, and P.1 versus wildtype (p<0.05). CONCLUSIONS: We report the first known evidence of impaired functional humoral responses following COVID-19 vaccines in patients with MM and WM. Overall, WM patients showed more severe impairment of COVID-19 S Ab responses. Most previously untreated WM patients achieved S Ab responses, however the most significant reduction in S Ab responses were seen in WM patients who received rituximab within 12 months or active BTK inhibitors. For MM patients, being in disease remission associated with improved S Ab response. Among MM and WM patients, age 375 years associated with significantly lower rates and vaccination with MRNA-1273 (Moderna) elicited significantly higher S Ab response rates than other vaccines. A defect in ADNP and more profound defect in ADCP suggests overall compromised opsinophagocytic activity among MM and WM patients. Data comparing first and second vaccine responses in MM patients, suggest less efficient class switching to IGG as well as incomple e maturation of their FcgR2A binding profiles but normal maturation of FcgR3A. Interestingly, ADCP was improved in several emerging SARS-CoV-2 variants. T-cell studies are pending and will be updated. Further understanding of the immunological response to COVID19 vaccination is needed to clarify patients risks, and necessity for booster or alternative protective measures against COVID-19. (Figure Presented).
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[Formula presented] Introduction Vaccine-induced thrombotic thrombocytopenia (VITT) is a severe complication of recombinant adenoviral vector vaccines used to prevent COVID-19, likely due to anti-platelet factor 4 (PF4) IgG antibodies. The specificity and platelet-activating activity of VITT antibodies strikingly resemble that of antibodies detected in “autoimmune” heparin-induced thrombocytopenia (HIT), but their features remain poorly characterized. In particular, a better knowledge of these antibodies should help to understand the mechanisms leading to hypercoagulability and the particular thrombotic events observed in VITT, but rarely in typical HIT. We have recently developed a chimeric IgG1 anti-PF4 antibody, 1E12, which strongly mimics “autoimmune” HIT antibodies in terms of specificity and cellular effects. Therefore, we assessed whether 1E12 could mimic VITT antibodies. We then evaluated the capability of DG-1E12, a deglycosylated form of 1E12 unable to bind FcγR, to inhibit cellular activation induced by VITT antibodies. Methods and Results Using a PF4-sensitized serotonin release assay (PF4-SRA) (Vayne C, New Engl J Med, 2021), we demonstrated that 1E12 (5 and 10 μg/mL) strongly activated platelets, with a pattern similar to that obtained with human VITT samples (n=7), i.e. in a PF4-dependent manner and without heparin. This platelet activation was inhibited by low heparin concentration (0.5 IU/mL), an effect also observed with VITT samples. Serotonin release induced by 1E12 was also fully inhibited by IV-3, a monoclonal antibody blocking FcγRIIa, or by IdeS, a bacterial protease that cleaves IgG and strongly inhibits the binding of IgG antibodies to FcγRIIa. This inhibitory effect of IV-3 and IdeS strongly supports that interactions between pathogenic anti-PF4 IgG and FcγRIIa play a central role in VITT. Incubation of 1E12 or VITT samples with isolated neutrophils (PMN) and platelets with PF4 (10 µg/mL) strongly induced DNA release and NETosis, supporting that PMN are involved in the processes leading to thrombosis in VITT. Furthermore, when whole blood from healthy donors incubated with 1E12 or VITT plasma was perfused in capillaries coated with von Willebrand Factor, numerous large platelet/leukocyte aggregates containing fibrin(ogen) were formed. To investigate whether 1E12 and VITT antibodies recognize overlapping epitopes on PF4, we then performed competitive assays with a deglycosylated form of 1E12 (DG-1E12), still able to bind PF4 but not to interact with Fcγ receptors. In PF4-SRA, pre-incubation of DG-1E12 (50 µg/mL) dramatically reduced platelet activation induced by VITT antibodies, which was fully abrogated for 9 of the 14 VITT samples tested. Additional experiments using a whole blood PF4-enhanced flow cytometry assay recently designed for VITT diagnosis (Handtke et al, Blood 2021), confirmed that DG-1E12 fully prevented platelet activation induced by VITT antibodies. Moreover, when platelets and neutrophils were pre-incubated with DG-1E12 (100 µg/mL), NETosis and thus DNA release, nuclear rounding, and DNA decondensation induced by VITT antibodies were completely inhibited. Finally, DG-1E12 (100 µg/mL) also fully abolished VITT antibody-mediated thrombus formation in whole blood in vitro under vein flow conditions. Comparatively, DG-1E12 did not inhibit ALB6, a murine monoclonal anti-CD9 antibody, which also strongly activates platelets in a FcγRIIa-dependent manner. Conclusions Our results show that 1E12 exhibits features similar to those of human VITT antibodies in terms of specificity, affinity and cellular effects, and could therefore be used as a model antibody to study the pathophysiology of VITT. Our data also demonstrate that DG-1E12 prevents blood cell activation and thrombus formation induced by VITT antibodies, likely due to the competitive effect of its Fab fragment on antibody binding to PF4. DG-1E12 may allow the development of a new drug neutralizing the pathogenic effect of autoimmune anti-PF4 antibodies, such as those associated with VITT. Disclosures: T iele: Bristol Myers Squibb: Honoraria, Other;Pfizer: Honoraria, Other;Bayer: Honoraria;Chugai Pharma: Honoraria, Other;Novo Nordisk: Other;Novartis: Honoraria;Daichii Sankyo: Other. Pouplard: Stago: Research Funding. Greinacher: Macopharma: Honoraria;Biomarin/Prosensa: Other, Research Funding;Sagent: Other, Research Funding;Rovi: Other, Research Funding;Gore inc.: Other, Research Funding;Bayer Healthcare: Other, Research Funding;Paringenix: Other, Research Funding;BMS: Honoraria, Other, Research Funding;MSD: Honoraria, Other, Research Funding;Boehringer Ingelheim: Honoraria, Other, Research Funding;Aspen: Honoraria, Other, Research Funding;Portola: Other;Ergomed: Other;Instrument Laboratory: Honoraria;Chromatec: Honoraria. Gruel: Stago: Other: symposium fees, Research Funding. Rollin: Stago: Research Funding.
ABSTRACT
Background: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a severe prothrombotic complication of adenoviral vaccines including ChAdOx1 nCoV-19 (AstraZeneca) vaccine. The putative mechanism involves formation of pathological anti-PF4 antibodies that activate platelets via the FcγRIIa receptor to drive thrombosis and the associated thrombocytopenia. Functional assays are important in the VITT diagnostic pathway as not all detectable PF4 antibodies are pathogenic. Detection of procoagulant platelets (platelets supporting thrombin generation) in presence of PF4 has been proposed as a diagnostic assay for VITT (Althaus et al). Procoagulant platelets are not typically generated in response to low level agonist stimulation;however, combination of ligand binding of G-protein coupled receptors (GPCR) (eg. PAR1) and ITAM linked receptors (eg. GPVI, CLEC2 and FcγRIIa) synergistically induce procoagulant platelet formation. Here, we describe an alternative flow cytometric assay to diagnose VITT. We hypothesized that priming of platelets with a PAR1 agonist at a level sufficient to release PF4, but insufficient to generate a significant procoagulant response in donor platelets, would provide a platform in which procoagulant response would be dependent on presence of FcγRIIa dependent procoagulant antibodies in patient plasma, without requirement for additional PF4. Methods: Our previously established flow cytometry-based procoagulant platelet assay (using cell death marker GSAO and P-selectin) was modified to incorporate exogenous patient plasma and performed on whole blood from healthy donors screened for FcγRIIa responsiveness (aggregation response to anti-CD9 antibody, ALB6), primed with 5 μM SFLLRN. The assay was performed on Australian patients referred for confirmatory VITT testing with probable VITT (confirmed thrombosis within 4-42 days of ChAdOx1 nCov-19 vaccination, D-Dimer > 5x ULN, platelets < 150 x 10 9/L or falling platelet count) after screening on PF4/heparin ELISA (Asserachrom HPIA IgG Assay, Stago Diagnostics). Procoagulant response was also measured in presence of 0.5 U/mL and 100 U/mL heparin, monoclonal FcγRIIa blocking antibody, IV.3, and intravenous immunoglobulin, IVIg. Some plasmas were incubated with ChAdOx1 nCoV-19 or SARS-CoV-2 spike protein. Flow cytometry positive patients were also tested by serotonin release assay (SRA) and multiplate aggregometry. Clinical correlation was obtained. Results: Citrated plasma from 49 unique patients with suspected VITT are reported. Plasma from ELISA+ve patients with clinical picture consistent with VITT (n=31), significantly increased the procoagulant platelet proportions in healthy donors in presence of 5 μM SFLLRN (p<0.0001, Figure 1A). This increase was not seen with plasma from healthy donors (n=14);or individuals exposed to ChAdOx1 nCov-19 vaccine without VITT: thrombocytopenic thrombosis patients who were ELISA-ve and SRA-ve (n=14);or low-level ELISA+ve patients without thrombocytopenia who were negative by either multiplate or SRA (n=4). The procoagulant platelet response induced by VITT positive plasma was reduced with low dose heparin (0.5 U/mL, p<0.01) except for 3 patients who showed a heparin-enhancing effect (Figure 1B). High dose heparin (100 U/mL, p<0.0001), IV.3 (10 µg/mL, p<0.0001) or IVIg (10 mg/mL, p<0.0001) abolished the procoagulant response (Figures 1C-D). The in vitro effect of IVIg was predictive of the in vivo response to IVIg therapy (Figure 1E). Addition of SARS-CoV-2 spike protein had no effect on the procoagulant platelet response. ChAdOx1 nCov-19 had an inconsistent effect on procoagulant platelet formation in presence of VITT plasma. Use of donors without a robust aggregation response to ALB6 resulted in false negative results. Conclusion: Induction of FcγRIIa dependent procoagulant response by patient plasma, suppressible by high dose heparin and IVIg, is highly indicative of VITT in the correct clinical circumstance. This assay modification of priming donor platelets from known FcγRIIa responsive donors ith a GPCR agonist to potentiate the ITAM signaling from platelet activating immune complexes, results in a sensitive and specific assay. This may represent a functional platform that can be adopted into diagnostic laboratories to identify patients with platelet-activating antibodies and potentially predict treatment responses. [Formula presented] Disclosures: No relevant conflicts of interest to declare.
ABSTRACT
Introduction: After spring 2020, a series of reports from Europe and USA described clusters of children, presenting life-threatening multisystem inflammatory syndrome in children (MIS-C), associated with antecedent exposure to SARS-CoV-2 (1). In patients with life threatening COVID-19 3.5% were found to have inborn errors in type I IFN signalling pathway (2). A case series of 4 young patients with severe COVID-19 reported rare loss-of-function variants in the TLR7 gene associated with impaired type I IFN responses (3). Clinically, MIS-C shares features with secondary hemophagocytic lymphohistiocytosis (HLH) and Kawasaki disease (KD), which were also associated with possible infectious trigger and might share a common genetic cause (4). Objectives: We analysed whether MIS-C patients have an underlying presence of genetic variants in exomes associated with inborn errors of type I IFN immunity, HLH, KD and presence of variants in TLR7 gene. Methods: Blood was drawn from 17 MIS-C patients upon submission into the hospital, DNA from peripheral blood was isolated and whole exome sequencing was performed. Variants in the following genes were investigated: type I IFN immunity (TLR3, UNC93B1, TRAF3, TBK1, IRF3/9, IRF7, IFNAR1/2, STAT1/2, IKBKG, TRIF), HLH (AP3B1, CD27, FADD, FAS, FASLG, HPLH1, ITK, LYST, MAGT1, MYO5A, NLRC4, PRF1, RAB27A, RECQL4, SH2D1A, STX11, STXBP2, UNC13D, XIAP, TNFRSF9, CDC42), KD (ITPKC, CD40, FCGR2A, BLK, CASP3, TRX-CAT1-7, PGBD1, LTA, TSBP1, HLA-DQB1/2, HLA-DOB, IGHV1-69) and TLR7 genes. Analysis was focused on rare (GnomAD<0.01) exonic or splicing variants. Results: No common genetic denominators were found in analysed genes. Five rare variants were observed in four patients (4/17). According to ACMG classification variants of uncertain significance (VUS) were found in LYST (2), IKBKG (1), IRF3 (1) and NLRC4 (1) in heterozygous genotype. No clinical evidence was found in ClinVar database for any of the variants, except for one variant in LYST (c.3931A>G:p.M1311V) with uncertain significance for Chédiak-Higashi syndrome and medium prediction scores. Variants in LYST (c.5990C>G:p.A1997G), NLRC4 (c.772T>C:p.C258R) and IRF3 (c.325G>C: p.G109R) have high CADD, Mutation Taster, Polyphen and SIFT prediction scores. And IKBKG (c.325C>G:p.L109V) variant had medium prediction scores. Conclusion: Our findings suggest that MIS-C patients do not share a rare loss-of-function variant in type I IFN immunity genes, TLR7 gene or genes associated either with HLH or KD. Despite numerous clinical, immunological and genetic research of the MIS-C patients, the syndromes pathogenesis and etiologic cause remain elusive.