IgG₄ is a subclass of IgG. Elevated serum IgG₄ levels are an important serological feature of IgG₄ related diseases and serve as a serological marker for assessing disease activity and severity. The harmonization of IgG₄ detection is crucial for its clinical application. National Clinical Research Center for Dermatologic and Immunologic Diseases (Peking Union Medical College Hospital), Experimental Diagnosis Research Committee, Rheumatology and Immunology Physicians Committee of Chinese Medical Doctor Association, Autoantibodies Detection Committee, and Chinese Rheumatism Data Center have organized clinical and laboratory experts to draft this consensus, aiming to standardize IgG₄ detection and provide guideline for clinician and laboratory experts to appropriate utility and interpret IgG₄ results in China.
Humans ; China ; Consensus ; Immunoglobulin G/blood*

Humans ; Larynx ; Immunoglobulin G4-Related Disease ; Immunoglobulin G

The emerging of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused COVID-19 pandemic. The first case of COVID-19 was reported at early December in 2019 in Wuhan City, China. To examine specific antibodies against SARS-CoV-2 in biological samples before December 2019 would give clues when the epidemic of SARS-CoV-2 might start to circulate in populations. We obtained all 88,517 plasmas from 76,844 blood donors in Wuhan between 1 September and 31 December 2019. We first evaluated the pan-immunoglobin (pan-Ig) against SARS-CoV-2 in 43,850 samples from 32,484 blood donors with suitable sample quality and enough volume. Two hundred and sixty-four samples from 213 donors were pan-Ig reactive, then further tested IgG and IgM, and validated by neutralizing antibodies against SARS-CoV-2. Two hundred and thirteen samples (from 175 donors) were only pan-Ig reactive, 8 (from 4 donors) were pan-Ig and IgG reactive, and 43 (from 34 donors) were pan-Ig and IgM reactive. Microneutralization assay showed all negative results. In addition, 213 screened reactive donors were analyzed and did not show obviously temporal or regional tendency, but the distribution of age showed a difference compared with all tested donors. Then we reviewed SARS-CoV-2 antibody results from these donors who donated several times from September 2019 to June 2020, partly tested in a previous published study, no one was found a significant increase in S/CO of antibodies against SARS-CoV-2. Our findings showed no SARS-CoV-2-specific antibodies existing among blood donors in Wuhan, China before 2020, indicating no evidence of transmission of COVID-19 before December 2019 in Wuhan, China.
Humans ; Antibodies, Viral ; Blood Donors ; China/epidemiology* ; COVID-19/immunology* ; Immunoglobulin G ; Immunoglobulin M ; Pandemics ; SARS-CoV-2

OBJECTIVE: This study prospectively investigates the association between immunoglobulin G (IgG) N-glycan traits and ischemic stroke (IS) risk. METHODS: A nested case-control study was conducted in the China suboptimal health cohort study, which recruited 4,313 individuals in 2013-2014. Cases were identified as patients diagnosed with IS, and controls were 1:1 matched by age and sex with cases. IgG N-glycans in baseline plasma samples were analyzed. RESULTS: A total of 99 IS cases and 99 controls were included, and 24 directly measured glycan peaks (GPs) were separated from IgG N-glycans. In directly measured GPs, GP4, GP9, GP21, GP22, GP23, and GP24 were associated with the risk of IS in men after adjusting for age, waist and hip circumference, obesity, diabetes, hypertension, and dyslipidemia. Derived glycan traits representing decreased galactosylation and sialylation were associated with IS in men (FBG2S2/(FBG2 + FBG2S1 + FBG2S2): odds ratio ( OR) = 0.92, 95% confidence interval ( CI): 0.87-0.97; G1 ⁿ: OR = 0.74, 95% CI: 0.63-0.87; G0 ⁿ: OR = 1.12, 95% CI: 1.03-1.22). However, these associations were not found among women. CONCLUSION This study validated that altered IgG N-glycan traits were associated with incident IS in men, suggesting that sex discrepancies might exist in these associations.
Male ; Humans ; Female ; Immunoglobulin G/metabolism* ; Ischemic Stroke ; Case-Control Studies ; Cohort Studies ; Glycosylation ; Polysaccharides

Objective To investigate the preventive therapeutic effect and possible mechanism of single chain variable fragments chimeric protein (SD) of ovalbumin epitopes internalizing receptor DEC-205 antibody on food allergy in mice. Methods Mice were randomly divided to five groups (control, PBS, scFv DEC 100 μg, SD 50 μg, SD 100 μg) and treated for 24 hours before OVA administration. After challenge, the serum level of OVA-specific IgE, IgG1, IgG2a and IL-4 were detected by ELISA. Infiltration of eosinophils and mast cells in the jejunum was observed by HE staining and toluidine blue staining respectively. The bone marrow of tibia and femur was isolated and cultured to obtain immature dendritic cells(BMDCs), which were further treated with LPS (10 ng/mL), TSLP (50 ng/mL), scFv DEC protein (1000 ng/mL) and SD protein (10,100,1000)ng/mL for 24 hours, and the IL-10 level of supernatant was assayed by ELISA. Results Compared with PBS group, the number of SD-treated mice with diarrhea was markedly reduced. The difference in rectal temperature and the levels of serum OVA-specific IgE, IgG1, IgG2a and IL-4 decreased significantly after prophylactic administration of SD; The number of eosinophils and mast cells in jejunum also decreased significantly while the IL-10 level in the supernatant of BMDCs increased significantly after SD intervention. Conclusion SD mitigates experimental FA response by fosters the immune tolerance property of dendritic cells.
Mice ; Animals ; Ovalbumin ; Interleukin-10 ; Single-Chain Antibodies/genetics* ; Immunoglobulin E ; Epitopes/therapeutic use* ; Interleukin-4 ; Food Hypersensitivity/prevention & control* ; Immunoglobulin G ; Recombinant Fusion Proteins/genetics* ; Mice, Inbred BALB C ; Disease Models, Animal

Objective To investigate the relationship between disease courses and severity and monocyte subsets distribution and surface CD31 intensity in patients of hemorrhagic fever with renal syndrome (HFRS). Methods Peripheral blood samples from 29 HFRS patients and 13 normal controls were collected. The dynamic changes of classical monocyte subsets (CD14⁺⁺CD16^-), intermediated monocyte subsets (CD14⁺⁺CD16⁺) and non-classical monocyte subsets (CD14⁺CD16⁺⁺) and the mean fluorescent intensity (MFI) of CD31 on monocyte subsets were detected by multiple-immunofluorescent staining and flow cytometry. Results In acute phase of HFRS, the ratio of classical monocyte subsets to total monocytes was dramatically decreased compared to convalescent phase and normal control. It was still much lower in convalescent phase compared to normal controls. The ratio of classical monocyte subsets to total monocytes were decreased in HFRS patients compared to that in normal control, whereas there was no difference between severe/critical groups and mild/moderate groups. On the contrary, the ratio of intermediate monocyte subsets to total monocytes in acute phase of HFRS was significantly increased compared to convalescent phase and normal control. The ratio of intermediate monocyte subsets to total monocytes were increased in HFRS patients compared to that in normal control, whereas no difference was found between severe/critical groups and mild/moderate groups. Phases or severity groups had no difference in ratio of non-classical monocyte subsets to total monocytes. Additionally, the ratio of classical monocyte subsets had a tendency to decline and that of intermediate monocyte subsets showed an increase both to total monocytes between the acute and convalescent phases in 11 HFRS patients with paired-samples. Moreover, in acute phase of HFRS, the mean fluorescent intensity (MFI) of CD31 on three monocyte subsets all decreased, specifically classical monocyte subsets showed the highest MFI of CD31 while the normal control reported the highest MFI of CD31 in non-classical monocyte subsets. In convalescent phase, the MFI of CD31 on classical and intermediated monocyte subsets were both lower than that of normal control, while MFI of CD31 was still significantly lower than normal control on non-classical monocyte subsets. Finally, MFI of CD31 on classical and intermediated monocyte subsets in severe/critical group were both lower than those in mild/moderate group, showing no statistical difference in MFI of CD31 on non-classical monocyte subset across groups of different disease severity. Conclusion The ratio of classical and intermediated monocyte subsets to total monocytes are correlated with the course of HFRS, and so are the surface intensity of CD31 on these monocyte subsets with the disease course and severity. The surface intensity of CD31 on non-classical monocyte subsets, however, is correlated only with the course of the disease. Together, the underlying mechanisms for the observed changes in monocyte subsets in HFRS patients should be further investigated.
Humans ; Monocytes ; Lipopolysaccharide Receptors ; Hemorrhagic Fever with Renal Syndrome ; Receptors, IgG ; Disease Progression

Objective To prepare specific mouse monoclonal antibody (mAb) against human adenovirus type 55 Hexon protein (HAdV55 Hexon). Methods The Hexon genes of HAdV55, 3, 4, 7, 16 and 21 were chemically synthesized as templates for PCR amplification. The prokaryotic expression plasmids pET28a-HAdV55 Hexon and eukaryotic expression plasmids pCAGGS-HAdV3, 4, 7, 16, 21 and 55 Hexon were constructed respectively. The pET28a-HAdV55 Hexon plasmid was transformed into E. coli competent cell BL21 (DE3) and was induced by IPTG. After the purified inclusion body was denatured and renatured, Hexon55 protein was purified by tangential flow filtration system. pCAGGS-HAdV55 Hexon was used to immunize BALB/c mice by cupping, and HAdV55 Hexon protein was used to booster immunization. The anti-HAdV55 Hexon mAb was prepared by hybridoma technique and the titer and subclass were determined. The specificity of antibody was identified by Western blot using HEK293T cells transfected with pCAGGS-HAdV55 Hexon and by immunofluorescence assay (IFA) using BHK cells transfected with pCAGGS-HAdV55 Hexon. Both clones with high titer were selected, and the cross-reactivity of pCAGGS-HAdV3, 4, 7, 16, 21 and 55 Hexon transfected cells were analyzed by Western blot analysis and IFA. Results PET28a-HAdV55 Hexon and pCAGGS-HAdV55 Hexon, 3, 4, 7, 16 and 21 expression plasmids were successfully constructed. BL21 transformed with pET28a-HAdV55 Hexon was induced by IPTG. The HAdV55 Hexon protein was mainly expressed in the form of inclusion body. After denaturation and renaturation, the purified HAdV55 Hexon protein was obtained by ultrafiltration. Six hybridoma cell lines secreting HAdV55 Hexon mAb were obtained. The antibody subclass analysis showed that 2 strains were IgG2a subtypes and 4 strains were IgG2b. Two specific HAdV55 Hexon antibodies with high titer were obtained, and there was no cross-reactivity with HAdV3, 4, 7, 16, 21 Hexon. Conclusion The specific mice mAb against HAdV55 Hexon provides an experimental basis for establishing its antigen detection method.
Animals ; Mice ; Humans ; Adenoviruses, Human/genetics* ; Escherichia coli/genetics* ; HEK293 Cells ; Isopropyl Thiogalactoside ; Blotting, Western ; Immunoglobulin G ; Antibodies, Monoclonal ; Antibody Specificity ; Mice, Inbred BALB C

OBJECTIVES: To investigate the clinical manifestations and laboratory examination results of children with Kawasaki disease complicated by macrophage activation syndrome (KD-MAS), and to provide a basis for identifying early warning indicators for the early diagnosis and treatment of KD-MAS. METHODS: A retrospective study was performed on 27 children with KD-MAS (KD-MAS group) and 110 children with KD (KD group) who were admitted to Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science and Technology, from January 2014 to January 2022. Clinical and laboratory data were compared between the two groups. The receiver operating characteristic (ROC) curve was used to investigate the value of laboratory markers with statistical significance in the diagnosis of KD-MAS. RESULTS: Compared with the KD group, the KD-MAS group had significantly higher incidence rates of hepatomegaly, splenomegaly, incomplete KD, no response to intravenous immunoglobulin, coronary artery damage, multiple organ damage, and KD recurrence, as well as a significantly longer length of hospital stay (P<0.05). Compared with the KD group, the KD-MAS group had significantly lower levels of white blood cell count, absolute neutrophil count, hemoglobin, platelet count (PLT), erythrocyte sedimentation rate, serum albumin, serum sodium, prealbumin, and fibrinogen (FIB), a significantly lower incidence rate of non-exudative conjunctiva, and significantly higher levels of C-reactive protein, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase (LDH), and serum ferritin (SF) (P<0.05). The ROC curve analysis showed that SF, PLT, FIB, and LDH had high value in the diagnosis of KD-MAS, with areas under the curve (AUC) of 0.989, 0.966, 0.932, and 0.897, respectively (P<0.001), and optimal cut-off values of 349.95 μg/L, 159×10⁹/L, 3.85 g/L, and 403.50 U/L, respectively. The combination of SF, PLT, FIB, and LDH had a larger AUC than PLT, FIB, and LDH alone in the diagnosis of KD-MAS (P<0.05), but there was no significant difference in the AUC between the combination of SF, PLT, FIB, and LDH and SF alone (P>0.05). CONCLUSIONS KD-MAS should be considered when children with KD have hepatosplenomegaly, no response to intravenous immunoglobulin, coronary artery damage, and KD recurrence during treatment. SF, PLT, FIB, and LDH are of high value in the diagnosis of KD-MAS, especially SF is of great significance in the diagnosis of KD-MAS.
Child ; Humans ; Immunoglobulins, Intravenous ; Macrophage Activation Syndrome/etiology* ; Mucocutaneous Lymph Node Syndrome/diagnosis* ; Retrospective Studies ; Blood Sedimentation ; Hepatomegaly

OBJECTIVES: To develop a risk prediction model for severe adenovirus pneumonia (AVP) in children, and to explore the appropriate timing for intravenous immunoglobulin (IVIG) therapy for severe AVP. METHODS: Medical data of 1 046 children with AVP were retrospectively analyzed, and a risk prediction model for severe AVP was established using multivariate logistic regression. The model was validated with 102 children with AVP. Then, 75 children aged ≤14 years who were considered at risk of developing severe AVP by the model were prospectively enrolled and divided into three groups (A, B and C) in order of visit, with 25 children in each group. Group A received symptomatic supportive therapy only. With the exception of symptomatic supportive therapy, group B received IVIG treatment at a dose of 1g/(kg·d) for 2 consecutive days, before progressing to severe AVP. With the exception of symptomatic supportive therapy, group C received IVIG treatment at a dose of 1 g/(kg·d) for 2 consecutive days after progressing to severe AVP. Efficacy and related laboratory indicators were compared among the three groups after treatment. RESULTS: Age<18.5 months, underlying diseases, fever duration >6.5 days, hemoglobin level <84.5 g/L, alanine transaminase level >113.5 U/L, and co-infection with bacteria were the six variables that entered into the risk prediction model for severe AVP. The model had an area under the receiver operating characteristic curve of 0.862, sensitivity of 0.878, and specificity of 0.848. The Hosmer-Lemeshow test showed good consistency between the predicted values and the actual observations (P>0.05). After treatment, group B had the shortest fever duration and hospital stay, the lowest hospitalization costs, the highest effective rate of treatment, the lowest incidence of complications, the lowest white blood cell count and interleukin (IL)-1, IL-2, IL-6, IL-8, IL-10 levels, and the highest level of tumor necrosis factor alpha (P<0.05). CONCLUSIONS The risk model for severe AVP established in this study has good value in predicting the development of severe AVP. IVIG therapy before progression to severe AVP is more effective in treating AVP in children.
Child ; Humans ; Immunoglobulins, Intravenous/therapeutic use* ; Prospective Studies ; Retrospective Studies ; Adenoviridae Infections/drug therapy* ; Pneumonia, Viral/drug therapy* ; Adenoviridae

Immune thrombocytopenia (ITP) is an immune-mediated acquired hemorrhagic autoimmune disease. At present, the first-line therapeutic drugs for ITP include glucocorticoids and intravenous immunoglobulins. However, about 1/3 of the patients had no response to the first-line treatment, or relapsed after dose reduction or withdrawal of glucocorticoids. In recent years, with the gradual deepening of the understanding on the pathogenesis of ITP, the drugs targeting different pathogenesis continually emerge, including immunomodulators, demethylating agents, spleen tyrosine kinase (SYK) inhibitors and neonatal Fc receptor (FcRn) antagonist. However, most of these drugs are in clinical trials. This review summarized briefly the recent advances in the treatment of glucocorticoids resistance and relapsed ITP, so as to provide reference for the clinical treatments.
Infant, Newborn ; Humans ; Purpura, Thrombocytopenic, Idiopathic/drug therapy* ; Glucocorticoids/therapeutic use* ; Thrombocytopenia ; Immunoglobulins, Intravenous/therapeutic use* ; Immunologic Factors/therapeutic use*