IgG1 and IgG4 antibodies against core and NS3 antigens of hepatitis C virus

Abstract INTRODUCTION: IgG subclasses involved in the immune response to hepatitis C virus (HCV) antigens have been rarely studied. We investigated the immune response mediated by IgG1 and IgG4 antibodies against the recombinant core and NS3 antigens in patients with chronic hepatitis C. METHODS: Sixty patients infected with HCV genotype 1 without antiviral treatment and 60 healthy subjects participated in the study. Serum levels of alanine aminotransferase, HCV viremia, and the presence of cryoglobulinemia and liver fibrosis were determined. We investigated the serum IgG1 and IgG4 antibodies against recombinant HCV core and NS3 non-structural protein antigens using amplified indirect ELISA. RESULTS: Anti-core and anti-NS3 IgG1 antibodies were detected in 33/60 (55%) and 46/60 (77%) patients, respectively, whereas only two healthy control samples reacted with an antigen (NS3). Anti-core IgG4 antibodies were not detected in either group, while 30/60 (50%) patients had anti-NS3 IgG4 antibodies. Even though there were higher levels of anti-NS3 IgG4 antibodies in patients with low viremia (< 8 × 105 IU/mL), IgG1 and IgG4 antibody levels did not correlate with ALT levels, the presence of cryoglobulinemia, or degree of hepatic fibrosis. High production of anti-core and anti-NS3 IgG1 antibodies was observed in chronic hepatitis C patients. In contrast, IgG4 antibodies seemed to only be produced against the NS3 non-structural antigen and appeared to be involved in viremia control. CONCLUSIONS: IgG1 antibodies against structural and non-structural antigens can be detected in chronic hepatitis C, while IgG4 antibodies seem to be selectively stimulated by non-structural HCV proteins, such as the NS3 antigen.

Immune Correlations in Chronic Child Urticaria.

Introduction: The growing prevalence of urticaria in children over the last decade and the importance of determining the involved pathogenic mechanisms as well as of detecting the etiologic factors are some of the aspects that led to the choice of research topic. Materials and Methods: The early diagnosis and the establishment of the therapeutic and prophylactic conduct in the urticaria are a necessity. There have been evaluated through a retrospective questionnaire, anamnesis and biochemical evaluation a number of 246 children diagnosed with chronic IgE and non IgE mediated urticaria, and prick tested for a wide range of food allergens. The assessment of the intensity of the eruption was done by calculating the urticaria activity score (UAS), both at diagnosis and at subsequent evaluations to assess the response to the treatment. The immunological investigations which were carried out included the determination of the IgA, IgG, IgM, total IgE and specific IgE to food allergens and airborne allergens, as well as the determination of the IgG4-type antibodies to 20 food allergens by means of enzyme immunoassay. The ELISA method was used for dosing the total IgE, while the CLA System Quanti Scan method (Innogenetics, Heiden, Germany) was used for determining the serum-specific IgE for 20 of the most common food allergens and airborne allergens (Innogenetics, Heiden, Germany). Results: Positive statistical correlations have been made with IgE and non IgE mediated reactions, also with IgG4 antibodies. The result of the multivariate analysis shows that the existence of the atopy represents a risk factor which significantly influences the allergic sensitisation (HR = 3.186 → 95% CI: 2.57-5.96), followed in the order of importance by food diversification before the age of 6 months (HR = 2.157 → 95% CI: 1.86-5.35), natural feeding before 3 months of age (HR = 1.78 → 95% CI: 1003-4581) and artificial or mixed feeding (HR = 1.56 → 95% CI: 1056-3861). Conclusion: There have been reported different correlations between specific IgE and IgG4 with different food allergens and the period of time between the onset and the duration of chronic urticaria. The regression of specific IgE has a predictive value upon the remission of urticaria (AUC=0.557, p=0.447, 95%CI: AUC→0.398–0.717). The logistic regression for analysis of the predictives factors for the regresson of urticaria showed several factors involved: Speciphic IgE values, compliance for the eliminating diet and treatment, allergic antecedents and the eventual polisensitivisation.