Food allergy. Manifestations, evaluation, and management

Natural history of food allergy in infants and children in Israel

BACKGROUND

Knowledge about the natural history of food allergy, especially sesame, is scarce.

OBJECTIVE

To follow the natural history of food allergies in Israel, particularly of sesame allergy.

METHODS

The survey was conducted based on clinical records and a detailed questionnaire of children diagnosed as having food allergy.

RESULTS

We found 234 children with suspected food allergy. Testing detected 283 allergies in 180 patients (77%) with confirmed diagnosis. The most common allergies were to cow's milk (n = 125), eggs (n = 71), sesame (n = 30), and soy (n = 23). Of those with milk allergy, 69% were IgE mediated (group 1) and 31% were non-IgE mediated (group 2). Group 1 was more likely to have an atopic background than was group 2 (P = .003), whereas group 2 was more likely to have resolution of the allergy (35 of 39 [90%] in group 2 compared with only 32 of 86 [37%] in group 1, P < .001). Allergy to soy was found in 23 children, of whom 87% manifested with gastrointestinal symptoms and 21 (91%) were also allergic to cow's milk. In 19 children (83%), the allergy resolved. Thirty children had allergy to sesame, and 73% of them had an atopic background. The allergy resolved in only 9 of these patients (30%) at a mean age of 2.8 years.

CONCLUSIONS

The distribution of food allergens in Israel differs from that in other countries. Non-IgE-mediated food allergy and particularly milk and soy allergy were likely to resolve completely with time. Sesame allergy was 1 of the most frequent in this cohort, was usually IgE mediated, and tended to resolve in only a few patients.

Chondroitin sulfate intake inhibits the IgE-mediated allergic response by down-regulating Th2 responses in mice

Chondroitin sulfate (CS) was administered orally to BALB/c mice immunized intraperitoneally with ovalbumin (OVA) and/or dinitrophenylated OVA. The titers of antigen-specific IgE and IgG1 in mouse sera were determined. The antigen-specific IgE production by mice fed ad libitum with CS was significantly inhibited. We also examined the effect of feeding CS on immediate-type hypersensitivity. One hour after antigen stimulation, the ears of mice fed with CS swelled less than those of the control mice. Furthermore, the rise in serum histamine in the mice fed with CS under active systemic anaphylaxis was significantly lower than that in the controls. We next examined the pattern of cytokine production by splenocytes from mice followed by re-stimulation with OVA in vitro. The splenocytes from the mice fed with CS produced less interleukin (IL)-5, IL-10, and IL-13 than those from the control group. In contrast, the production of interferon-gamma and IL-2 by the splenocytes of mice fed with CS was not significantly different from those in the control mice. In addition, the production of transforming growth factor-beta from the splenocytes of mice fed with CS was significantly higher than that of the control mice. Furthermore, we showed that the percentages of CD4(+) cells, CD8(+) cells, and CD4(+)CD25(+) cells in the splenocytes of mice fed with CS are significantly higher than those of the control. These findings suggest that oral intake of CS inhibits the specific IgE production and antigen-induced anaphylactic response by up-regulating regulatory T-cell differentiation, followed by down-regulating the Th2 response.

The Feeding of .BETA.-Carotene Down-Regulates Serum IgE Levels and Inhibits the Type I Allergic Response in Mice

Feed containing beta-carotene was administered orally to BALB/c mice immunized intraperitoneally with ovalbumin (OVA) for approximately 1 month. The titers of OVA-specific IgE, OVA-specific IgG1 and OVA-specific IgG2a in the mouse sera were determined. The OVA-specific IgE titer and OVA-specific IgG1 titer by mice fed beta-carotene were significantly inhibited. On the other hand, the OVA-specific IgG2a titer in mice fed beta-carotene was significantly greater than those of control mice. The OVA-specific IgE suppression of beta-carotene feeding was dose-dependent. We also examined the effect of fed beta-carotene on active systemic anaphylaxis. Feeding beta-carotene to mice immunized with OVA inhibited the immediate reduction of the body temperature induced by antigen stimulation. Furthermore, the increase in serum histamine in the mice fed beta-carotene under active systemic anaphylaxis was lower than in controls. We then examined the pattern of cytokine production by spleen cells from mice followed by restimulation with OVA in vitro. The spleen cells from the mice fed beta-carotene produced more IFN-gamma, IL-12 and IL-2 than those from the control group. In contrast, the spleen cells from the mice fed beta-carotene produced less IL-4, IL-5, IL-6, IL-10 than those from the control group. Furthermore, analysis of IFN-gamma mRNA levels of the splenocytes using the real-time quantitative RT-PCR technique revealed higher levels in the splenocytes from the mice fed beta-carotene. These findings suggest that feeding beta-carotene improves the helper T cell (T(H))1-T(H)2 balance, inhibiting specific IgE and IgG1 production and antigen-induced anaphylactic response.

Novel antiallergic catechin derivatives isolated from oolong tea

Two catechin derivatives (C-1 and C-2) with potent antiallergic activity were isolated from Taiwanese oolong tea by HPLC techniques. From NMR and FAB-MS analyses, the structures of C-1 and C-2 were elucidated as (-)-epigallocatechin 3-O-(3-O-methyl)gallate and (-)-epigallocatechin 3-O-(4-O-methyl)gallate, respectively. The oolong tea leaves contained 0.34% (dry weight) C-1 and 0.20% C-2. Traces of C-2 were detected in only 1 of 15 varieties of green tea tested. C-1 was detected in 13 of 15 green tea varieties; C-1 was most concentrated in tea cultivars classified as Assam hybrids (0. 50-0.82% of dry weight). Quantitative analyses of green tea, oolong tea, and black tea manufactured from same batches of tea leaves showed that neither catechin derivative was produced during the fermentation process. Oral doses of C-1 and C-2 (5-50 mg/kg) significantly inhibited type I allergic (anaphylactic) reactions in mice sensitized with ovalbumin and Freund's incomplete adjuvant. These inhibitory effects exceeded that of the major tea catechin, (-)-epigallocatechin 3-O-gallate, which has known antiallergic properties.

Management of food allergy

Our present options for the management of food allergy are avoidance and pharmacotherapy. There are, however, many promising perspectives for better future management such as the more extensive use of hydrolyzed and elemental formulas for therapy and prevention, or greater emphasis on diagnosis and treatment of accompanying diseases linked with increased gut permeability. In selected situations, specific immunotherapy might be helpful. Rapid progress is expected in the search for the conditions of induction of oral tolerance. The latest results in genetic engineering can give us very effective tools for mass production of less allergenic foods with high nutritional value--if all safety, stability, productivity, and antigenicity problems can be solved.

Effect of tea polyphenols on histamine release from rat basophilic leukemia (RBL-2H3) cells: the structure-inhibitory activity relationship

We studied the effect of tea polyphenols on histamine release from rat basophilic leukemia (RBL-2H3) cells. Among tea polyphenols, (-)- epigallocatechin gallate (EGCG) most strongly and dose-dependently inhibited histamine release from cells stimulated with a calcium ionophore, A23187. (-)-Epigallocatechin (EGC) and (-)-epicatechin gallate (ECG) with a triphenol residue moderately inhibited histamine release, whereas diphenolic (+)-catechin (C) and (-)-epicatechin (EC) did not. The magnitude of the inhibitory effect was in the order EGCG > ECG > EGC. Among simple polyphenols, the triphenol compounds, pyrogallol (PG) and gallic acid (GA) exerted inhibitory activity, but the diphenols, pyrocatechol, hydroquinone, and resorcinol did not. In addition, the mixture of PG and GA inhibited histamine release as strongly as EGCG with two triphenol residues. Similarly, they inhibited histamine release induced by IgE-antigen complex stimulation more efficiently than that induced by A23187 stimulation. EGCG did not inhibit the increase of intracellular Ca2+ in RBL-2H3 cells stimulated with A23187 or IgE antigen. These results indicate that the triphenol structure plays an important role in the inhibitory activity of tea polyphenols. Their activity seemed to be exerted through the metabolic events occurring after the elevation of intracellular Ca2+ concentration.

Inhibitory effect of tea polyphenols on histamine and leukotriene B4 release from rat peritoneal exudate cells

The effect of tea polyphenols on the release of chemical mediators, histamine and leukotriene B4 (LTB4), from rat peritoneal exudate cells (PEC) was studied. Among polyphenols, (-)-epigallocatechin gallate (EGCG) most strongly inhibited the histamine release from the cells stimulated with a calcium ionophore, A23187 or compound 48/80. Though (+)-catechin (C) and (-)-epicatechin (EC) had no effect, (-)-epigallocatechin (EGC) and (-)-epicatechin gallate (ECG) moderately inhibited the histamine release. Similarly, EGCG, ECG, and EGC inhibited LTB4 release from PEC, whereas C and EC were not effective. The magnitude of the inhibitory effect on the release of these mediators of tea polyphenols was in the order of EGCG > ECG > EGC. These results indicated an important role of the triphenol structure in the inhibitory activity. Therefore, the possible antiallergic effect of tea polyphenols can be expected.

Food allergy in children

The diagnosis of hypersensitivity reactions to foods in infancy and childhood requires the use of clinical skills and laboratory diagnostic methods to identify suspect foods. Patients and parents occasionally may need to keep food/symptom diaries to explore the association of foods and adverse reaction. Skin testing or RAST may shorten the list of potential allergens because of their excellent negative predictive value. Except for obvious serious allergic reactions after ingestion of a single food, confirmation of the reaction may be ideally confirmed by a DBPCFC, especially if the reported symptoms are subjective in nature. Equivocal responses should be repeated. Although many in vitro and in vivo diagnostic methods have been developed to potentially improve the diagnosis of food allergy in children, no test has been able to predict the results of the DBPCFC with any greater accuracy than skin tests or RAST. The "perfect" test with excellent positive and negative predictive values has yet to be developed.