The Inverse Association Between the Presence of Antibody to Hepatitis B Surface Antigen and Atopy in Young Adults

BACKGROUND: Some bacterial and viral infections may reduce the risk of atopy, and this is based on the concept of their ability to divert the immune system towards the Th1 responses. Most of the hepatitis B virus (HBV) infections occur in the developing countries and this is where atopic disorders are least prevalent. Th1 responses are important for the viral clearance of HBV and also for antibody production. The aim of the study is to investigate whether the presence of antibodies to the hepatitis B surface antigen (anti-HBs) is inversely associated with atopy in adults. METHODS: A random sample of 358 subjects, who were without hepatitis B surface antigen, was recruited; they were aged from 18 to 79 years (105 young adults aged 40 years). Determinations of the anti-HBs and skin prick tests using aeroallergens were performed. Those subjects with one or more positive skin reactions (a mean wheal diameter > or=3 mm) were considered atopic. RESULTS: The prevalence rate of atopy (p=0.035) or the sensitization to Dermatophagoides farinae (p=0.01) was significantly lower in the subjects with anti-HBs than in those subjects without anti-HBs for the young adults, but not for the older adults. The logistic regression analysis that was done on the young adults showed that the presence of anti-HBs was associated with a significantly lower risk of atopy (the odds ratio adjusted for confounding variables=0.40 [95% CI 0.16-0.98], p=0.046) or with the sensitization to D. farinae (0.20 [0.06-0.65], p=0.008). CONCLUSION: The presence of anti-HBs produced by a natural HBV infection or vaccination might be inversely associated with atopy in young adults.

Relationship between Dendritic Cells and Activated Eosinophils in Induced Sputum of Asthmatics

It has been suggested that dendritic cells (DCs) are critical antigen presenting cells for eosinophilic airway inflammation in a mouse model of asthma, and cysteinyl leukotrienes may play a role in DC trafficking in asthmatics. We investigated whether the number of DCs is increased in the induced sputum of both atopic and nonatopic asthmatics and is related to activated eosinophil count in the sputum. Sputum was induced by inhalation of hypertonic saline in 9 atopic and 12 nonatopic asthmatics and 10 nonatopic normal controls, and differential cell counts were performed. DCs and activated eosinophils were identified by immunocytochemistry with monoclonal antibodies (anti-CD1a and EG2, respectively). There were significantly higher percentages of eosinophils, EG2+ cells, and CD1a+ DC in the sputum of atopic and nonatopic asthmatics compared with normal controls, respectively. In asthmatics, the percentage of CD1a+ DC was significantly correlated with that of EG2+ cells (Rs=0.62, p=0.004). We demonstrated that the increased number of DCs was evident in the induced sputum of both atopic and nonatopic asthmatics, and the DC number was related to the activated eosinophil count, which suggests that DCs may contribute to the ongoing eosinophilic inflammation in asthmatic airways, and vice versa.