Do levels of immunoglobulin G antibodies to foods predict the development of immunoglobulin E antibodies to cat, dog and/or mite?

BACKGROUND: In children at high risk of inhalation allergy, food sensitization is associated with an increased risk for sensitization to inhalant allergens. Furthermore, this association was also found in a cross-sectional study. OBJECTIVE: To examine in a prospective study, whether levels of IgG to foods (i.e. mixture of wheat and rice, mixture of soy bean and peanut, egg white, cow's milk, meat, orange and potato) indicate an increased risk for the future development of IgE antibodies to inhalant allergens in a low-risk population and whether they can be used as predictors of the subsequent development of IgE antibodies in young, initially IgE-negative children. METHODS: Coughing children, aged 1-5, visiting their GPs, were tested for IgE antibodies to mite, dog and cat (RAST) and IgG (ELISA) to foods. All IgE-negative children were retested for IgE antibodies after two years. The IgG results (66 percentiles) of the first blood sample were compared to the RAST-scores of the second blood sample. RESULTS: After two years, 51 out of 397 (12.8%) originally IgE-negative children, had become IgE-positive for cat, dog and/or mite. An increased IgG antibody level to wheat-rice (OR = 2.2) and to orange (OR = 2.0) indicated an increased risk of developing IgE to cat, dog or mite allergens. In addition to IgG to a mixture of wheat-rice and orange; total IgE, breastfeeding, eczema as a baby and age were the most important predictors for the subsequent development of IgE to inhalant allergens. DISCUSSION: An increased IgG antibody level to a mixture of wheat-rice or orange, indicates an increased risk of developing IgE to cat, dog or mite allergens. This indicates that excessive activity of the mucosal immune system is present before IgE antibodies to airborne allergens can be demonstrated. Nevertheless, IgG to foods is not very helpful (with a positive predictive value of 16.5%, and negative predictive value of 90.6%) in identifying individual children at risk in clinical practice. However, besides other risk factors, IgG to wheat-rice and to orange could be useful as a screening test for studies in the early identification, i.e. before IgE antibodies can be detected, of children with an increased risk of developing IgE antibodies in the future.

Development of specific immunoglobulin E in coughing toddlers: a medical records review of symptoms in general practice.

The aim of this study was to study whether young children, originally immunoglobulin E (IgE) negative and who became sensitized to specific inhalation allergens, presented more frequently to their general practitioner (GP) with other allergy- and asthma-related symptoms than children who remained IgE negative. It was also investigated whether asthma was diagnosed more often in children who developed IgE to inhalant allergens. Coughing children, 1-5 years of age, visiting the participating GPs, were tested for IgE antibodies to mites, dogs, and cats by using radioallergosorbent testing (RAST). All IgE-negative (RAST < 0.2 IU/ml) children were re-tested after 2 years. The medical records of 162 children were reviewed on asthma- and allergy-related symptoms and on prescribed medication. After 30 months, 27 of the 162 children (17%) had become IgE positive for one or more allergens. Most children (93%) had visited their GP for treatment of respiratory symptoms during this period. However, the children who had become IgE positive had visited their GP more often than the children who remained IgE negative. Differences in visits were seen for: shortness of breath (52% IgE-positive vs. 19% IgE-negative children, respectively), wheeze (37% vs. 17%), allergic rhinitis (33% vs. 16%), and pneumonia (22% vs. 8%), but not for coughing (89% vs. 88%). The IgE-positive children were more frequently diagnosed by their GP as having asthma (48%) than were the IgE-negative children (23%). In a multivariate analysis, indicators of becoming IgE positive were: a visit for shortness of breath (odds ratio [OR] = 6.9; 95% confidence interval [CI] = 2.1-23.1) and two or more visits for wheeze (OR = 6.0; 95% CI = 1.9-19.2), adjusted for breast-feeding, age, and asthma or allergy in the family. The positive predictive value (PPV) of being IgE positive with a diagnosis of asthma was 90% (whereas the negative predictive value was 48.0%) for a child attending their GP for treatment of wheeze. For recurrent coughing (six or more visits) and shortness of breath, the PPVs were 73% and 71%, respectively. The development of sensitization to common inhalant allergens is associated with specific allergy and asthma-related symptoms in young children. IgE-positive children were more frequently diagnosed as having asthma by their GP. This implies that in general practice it is possible to detect children at high risk for developing allergic asthma early in life by their respiratory symptoms and by subsequent testing for specific IgE to inhalant allergens.

Hyperhomocysteinemia is associated with the presence of retinopathy in type 2 diabetes mellitus: the Hoorn study.

BACKGROUND: Retinopathy is the leading cause of blindness among patients with type 2 diabetes mellitus (DM). Hyperhomocysteinemia is a recently recognized risk factor for cardiovascular disease, independent of established risk factors. OBJECTIVE: To study the association between the homocysteine level and retinopathy among subjects with and without DM. METHODS: We studied an age-, sex-, and glucose tolerance-stratified random sample of a 50- to 75-year-old general white population in the Hoorn Study (N = 625). Retinal vascular changes (retinopathy) were assessed using ophthalmoscopy and/or fundus photography. Hyperhomocysteinemia was defined as a serum total homocysteine level greater than 16 micromol/L. RESULTS: The prevalence of retinopathy was 9.8% (28/285) in subjects with normal glucose tolerance, 11.8% (20/169) in those with impaired glucose tolerance, 9.4% (10/106) in those with newly diagnosed type 2 DM, and 32.3% (21/65) in those with known type 2 DM. The prevalence of retinopathy was 10.3% (39/380) in subjects without hypertension and 16.3% (40/245) in subjects with hypertension; it was 12.0% (64/534) in subjects with a serum total homocysteine level of 16 micromol/L or less and 16.5% (15/91) in those with a serum total homocysteine level of more than 16 micromol/L. After stratification for DM and adjustment for age, sex, glycosylated hemoglobin, and hypertension, the odds ratio (95% confidence interval) for the relation between retinopathy and hyperhomocysteinemia was 0.97 (95% confidence interval, 0.42-2.82) in patients without DM and 3.44 (95% confidence interval, 1.13-10.42) in patients with DM (P =.08 for interaction). CONCLUSION: The findings suggest that hyperhomocysteinemia may be a risk factor for retinopathy in patients with type 2 DM, but probably not in patients without DM. Arch Intern Med. 2000;160:2984-2990

Relation between IgG antibodies to foods and IgE antibodies to milk, egg, cat, dog and/or mite in a cross-sectional study.

BACKGROUND: Because IgG antibodies to foods can be detected before IgE antibodies to inhalants, increased levels of IgG antibodies to foods might be used as a predictor of IgE-mediated allergy in initially nonatopic children. OBJECTIVE: To examine the cross-sectional relation between IgG to foods (i.e. mixture of wheat and rice, mixture of soybean and peanut, egg white, cow's milk, meat, orange and potato) and specific IgE to cat, dog, mite, milk and egg white in 1-year-old children. METHODS: All atopic children (n = 120; 58 with and 62 without eczema) and a random sample of the nonatopic children (n = 144) of the Bokaal study were tested on their IgG response to foods. The IgG results of the food assays were dichotomized high or low using the 66th centile as a cut-off value. RESULTS: Atopic children more often had high IgG levels to foods than nonatopic children. IgG to egg white (OR = 7.50) and mixture of wheat and rice (OR = 4.79) were most strongly associated with positive specific IgE. In a stepwise logistic regression analysis egg white, mixture of wheat and rice, and orange were selected (OR = 3.76, OR = 2.43, and OR = 2.11, respectively). In children without eczema higher levels of IgG to foods were still significantly associated with atopy, which was most prominent for egg white, orange and cow's milk. CONCLUSION: An increased IgG antibody level to foods, especially to egg white, orange, and mixture of wheat and rice, indicates an increased risk of having IgE to cat, dog, mite, egg and/or milk allergens, even in the noneczematous group. Therefore, in another prospective study we are currently investigating the usefulness of IgG in early identification, i.e. before IgE antibodies can be detected, of children with an increased risk of developing allergic diseases in the future.