International survey on growth indices and impacting factors in children with food allergies.

BACKGROUND: Elimination diets required for the management of food allergies increase the risk for poor growth in children. Currently, no worldwide data exist on this topic and limited published data exist on the impact of atopic comorbidity, type of allergy and foods eliminated on growth. We therefore set out to perform a worldwide survey on growth and impacting factors in food allergic children. METHODS: A prospective growth survey was performed of children (aged 0-16 years) on an elimination diet with confirmed immunoglobulin (Ig)E and non-IgE mediated food allergies. Data collected included: weight-for-age, weight-for-height, height-for-age, head circumference, body mass index, type of food allergy and eliminated foods, allergic comorbidities and replacement milk/breast milk. Multivariable regression analysis was used to establish factors that affected growth. RESULTS: Data from 430 patients from twelve allergy centres were analysed: median age at diagnosis and data collection was 8 months and 23 months, respectively. Pooled data indicated that 6% were underweight, 9% were stunted, 5% were undernourished and 8% were overweight. Cow's milk elimination lead to a lower weight-for-height Z-scores than other food eliminations and mixed IgE and non-IgE mediated allergy had lower height-for-age Z-scores than IgE mediated allergy. Children with only non-IgE mediated allergies had lower weight-for-height and body mass index. Atopic comorbidities did not impact on growth. CONCLUSIONS: Stunting is more common in children with food allergies than low weight. Children particularly at risk of poor growth are those with non-IgE and mixed IgE and non-IgE mediated allergies, as well as those with cow's milk allergy.

Mutation analysis of the gene encoding Bruton's tyrosine kinase in a family with a sporadic case of X-linked agammaglobulinemia reveals three female carriers.

Bruton's tyrosine kinase (Btk) has been identified as the protein responsible for the primary immunodeficiency X-linked agammaglobulinemia (XLA). We and others have cloned the gene for Btk and recently reported the genomic organization. Nineteen exons were positioned within the 37 kb gene. With the sequence data derived from our genomic map, we have designed a PCR based assay to directly identify mutations of the Btk gene in germline DNA of patients with XLA. In this report, the assay was used to analyze a family with a sporadic case of XLA to determine if other female relatives carry the disease. A four base-pair deletion was found in the DNA of the affected boy and was further traced through three generations. With the direct identification of the mutations responsible for XLA, we can now diagnose conclusively the disease and identify the immunologically normal female carriers. This same technique can easily be applied to prenatal diagnosis in families where the mutation can be identified.

Effect of acellular pertussis vaccine on the development of allergic sensitization to environmental allergens in adults.

BACKGROUND: Exposure of children to pertussis antigens caused by infection or vaccination with whole-cell pertussis vaccine may increase the serum IgE level and predispose to sensitization to the prevalent environmental allergens. Acellular pertussis vaccine (APV) that may be given to adults may have a similar effect. OBJECTIVE: The purpose of this study was to determine whether APV will cause an increase in environmental sensitization measured by an increase of serum-specific IgE to the allergens to which adults are exposed during the vaccination period. METHODS: One hundred adult hospital employees were randomized to receive either a 2-component APV composed of pertussis toxin and filamentous hemagglutinin or a meningococcal vaccine as a control. Serum-specific IgE level to 2 indoor allergens, cat and dust mite, and 2 outdoor allergens prevalent during the immunization season, Alternaria species and ragweed, was measured by an RIA on sera collected before and 1 month after vaccination. RESULTS: The group that received the APV had no significant change in their serum-specific IgE levels to cat, dust, Alternaria species, or ragweed 1 month after vaccination. CONCLUSION: A 2-component APV did not predispose to an increase of allergen-specific IgE in an adult population.

Effect of superoxide dismutase on a rabbit model of chronic allergic asthma.

BACKGROUND: In bronchial asthma, inflammatory cells infiltrating the airway mucosa release oxygen radicals that cause tissue damage and amplify the airway inflammation. Antioxidant enzymes may have a protective effect on the airways. OBJECTIVE: The purpose of this study was to determine whether treatment of a rabbit model of chronic allergic asthma with the antioxidant enzyme superoxide dismutase conjugated to polyethylene glycol will protect the airways from oxygen radical injury, decrease airway inflammation, and attenuate the asthmatic response. METHODS: New Zealand white rabbits were sensitized to ragweed. Baseline histamine PC30, ragweed PD30, and early and late phase asthmatic response to ragweed bronchial challenge were measured. The rabbits were then randomized into two groups that received every 48 hours an intravenous dose of either superoxide dismutase-polyethylene glycol 10,000 U/kg or inactivated superoxide dismutase-polyethylene glycol as control, followed by a 1-hour exposure to aerosolized ragweed extract. After 4 weeks the rabbits had a second bronchial challenge, were sacrificed, and lung histology was studied. RESULTS: On the posttreatment challenge, the superoxide dismutase-polyethylene glycol group had a rise in ragweed PD30, while the control group had no change in ragweed PD30, and two of five rabbits in the superoxide dismutase-polyethylene glycol group did not have an early or late phase asthmatic response, while all rabbits in the control group had an asthmatic response. There was no significant difference in lung histology between both groups. CONCLUSION: A rabbit model of chronic allergic asthma treated with superoxide dismutase-polyethylene glycol showed a trend of improvement in airway responsiveness but no significant effect on airway inflammation.