Infant milk formulas differ regarding their allergenic activity and induction of T-cell and cytokine responses

Background

Several hydrolyzed cow's milk (CM) formulas are available for avoidance of allergic reactions in CM‐allergic children and for prevention of allergy development in high‐risk infants. Our aim was to compare CM formulas regarding the presence of immunoreactive CM components, IgE reactivity, allergenic activity, ability to induce T‐cell proliferation, and cytokine secretion.

Methods

A blinded analysis of eight CM formulas, one nonhydrolyzed, two partially hydrolyzed (PH), four extensively hydrolyzed (EH), and one amino acid formula, using biochemical techniques and specific antibody probes was conducted. IgE reactivity and allergenic activity of the formulas were tested with sera from CM‐allergic patients (n = 26) in RAST‐based assays and with rat basophils transfected with the human FcεRI, respectively. The induction of T‐cell proliferation and the secretion of cytokines in Peripheral blood mononuclear cell (PBMC) culture from CM allergic patients and nonallergic individuals were assessed.

Results

Immune‐reactive α‐lactalbumin and β‐lactoglobulin were found in the two PH formulas and casein components in one of the EH formulas. One PH formula and the EH formula containing casein components showed remaining IgE reactivity, whereas the other hydrolyzed formulas lacked IgE reactivity. Only two EH formulas and the amino acid formula did not induce T‐cell proliferation and proinflammatory cytokine release. The remaining formulas varied regarding the induction of Th2, Th1, and proinflammatory cytokines.

Conclusion

Our results show that certain CM formulas without allergenic and low proinflammatory properties can be identified and they may also explain different outcomes obtained in clinical studies using CM formulas.

Infant feeding and allergy prevention: a review of current knowledge and recommendations. A EuroPrevall state of the art paper

The relationship between infant feeding patterns and the later development of food allergies has been the focus of much debate and research over the last decade. National recommendations have been made by many countries on how to feed infants to reduce the risk of food allergy but due to the lack of firm evidence the recommendations differ widely. This review has been developed as part of EuroPrevall, a European multicentre research project funded by the European Union, to document the differing feeding recommendations made across Europe, to investigate the current evidence base for any allergy prevention feeding recommendations and to identify areas where further research is needed. This review will also provide information which, when combined with the infant feeding data collected as part of EuroPrevall, will give an indication of compliance to national feeding guidelines which can be utilised to assess the effectiveness of current dissemination and implementation strategies.

Factors influencing the incidence and prevalence of food allergy

Food allergy is an increasing problem in Europe and elsewhere and severe reactions to food are also becoming more common. As food allergy is usually associated with other forms of allergic sensitisation it is likely that many risk factors are common to all forms of allergy. However the potential severity of the disease and the specific public heath measures required for food allergy make it important to identify the specific risk factors for this condition. Food allergy is unusual in that it often manifests itself very early in life and commonly remits with the development of tolerance. Hypotheses that explain the distribution of food allergy include specific genetic polymorphisms, the nature of the allergens involved and the unique exposure to large quantities of allergen through the gut. Progress has been made in developing more specific and testable hypotheses but the evidence for any of these is still only preliminary. Further collaborative research is required to develop an appropriate public health response to this growing problem.

Higher immunoglobulin E antibody levels to recombinant Fel d 1 in cat-allergic children with asthma compared with rhinoconjunctivitis

BACKGROUND

Current diagnosis of allergy and asthma to cat is confirmed using cat dander extract (CDE). We have previously engineered a recombinant major cat allergen, rFel d 1, with properties identical to the natural molecule.

OBJECTIVE

The aim of the study was to evaluate IgE and IgG4 antibodies to rFel d 1 among sera from cat-allergic children and adults suffering from asthma and/or rhinoconjunctivitis (RC) in populations from Sweden and Austria.

METHODS

Cat-allergic children and adults from Sweden (n=27 and 31, respectively) and Austria (n=41 and 41) with RC and/or asthma were selected. Sera were tested for IgE and IgG4 antibodies to CDE and rFel d 1 by CAP, and IgE to rFel d 1 by ELISA. Healthy subjects and non-cat-allergic patients (n=75) were included as controls.

RESULTS

There was a high correlation between IgE responses to rFel d 1 and CDE among the 140 patients (r(s)=0.85, P<0.001); however, measured levels to rFel d 1 were on average 30% higher (P<0.0001). Ninety-eight percent of patients and none of the controls showed IgE to rFel d 1 and there was a threefold increased risk of asthma for half of the children with the highest IgE levels [odds ratio 3.23; 95% confidence interval (CI), 1.19-8.79] by ELISA. IgE responses to rFel d 1 among children with asthma were higher (median 19.4 kU/L) compared with children with RC (median 6.6 kU/L, P<0.05) and adults with asthma (median 3.0 kU/L, P<0.01). Furthermore, children with asthma displayed higher IgG4 levels than the asthmatic adults.

CONCLUSION

A single recombinant molecule, rFel d 1, is at least as sensitive for in vitro diagnostics of cat allergy as the current extract-based test. Elevated IgE antibody levels to Fel d 1 are suggested to be a risk factor for asthma in cat-allergic children.

[Early feeding in infancy and atopic dermatitis - a prospective observational study]

BACKGROUND

Recommendations for primary prevention of allergic diseases in high-risk children include hypoallergenic infant formulas (HA) if breastfeeding is insufficient. The primary objective of our study was to investigate the atopic dermatitis (AD) preventive effect of breastfeeding and HA-nutrition in the first 2 years of life and to follow the increase in weight.

PATIENTS AND METHODS

Altogether 174 newborns with a hereditary risk for atopy were enrolled in the study, 121 children were investigated at the age of 2 months, 111 at the age of 4 and 106 at the age of 6 months. A total of 45 infants were in the first half-year of life exclusively breastfed and 61 infants were mainly fed with HA.

RESULTS

The body weight of initially HA-fed children was 7870G (SD 949) significantly higher as the one of breastfed children (7508 G, SD 912, p=0.0571), in addition the weight increase was also significantly higher in HA-fed infants at the age of 6 months (p=0.0042). The frequency of AD as well as SCORAD score at the age of 6 to 24 months was comparable in both groups. Neither the milk-specific IgE antibodies nor the proliferation of peripheral blood mononuclear cells (PBMC) to bovine beta-Lactoglobulin (BLG) at the age of 6 months had a prognostic value for development of atopic dermatitis.

CONCLUSION

The likelihood to develop AD in the first 2 years of life was comparable in exclusively breastfed as in HA-fed infants with hereditary risk for atopy. The initially HA-fed children demonstrated at the age of 6 months higher body weight and weight increase as the exclusively breastfed infants. The efficacy of nutritional intervention on the incidence of AD in high-risk children for atopy could not be predicted by milk-specific IgE antibodies or BLG-specific proliferation of PBMC.

[Cow's milk allergy: guidelines for the diagnostic evaluation]

About 2% of the general population and up to 6% of children suffer from food allergy. Cow's milk is charged with a important role in infancy after weaning, since conventional formula are based on its procession. IgE-mediated and Non-IgE- mediated allergic reactions, which are different in manifestation and pathogenesis, can be distinguished. A special role play the exacerbation of atopic dermatitis and the gastrointestinal-food-hypersensitivity-reactions. Skin-prick-test and determination of specific IgE are important diagnostic tools beside medical history. The golden standard of diagnosis is the double-blind-placebo-controlled-food- challenge. The clear result from food-challenge allows to verify suspected food allergies or, on the other hand, to avoid unnecessary diets. Extensively-hydrolysed-formula or Amino-acidformula are a high nutritional value alternative in case of proved cow's milk allergy in infancy.

Molecular characterization of an autoallergen, Hom s 1, identified by serum IgE from atopic dermatitis patients

Atopy is a genetically determined disorder that affects 10%-20% of the population. Many symptoms of patients with atopy (allergic rhinitis, conjunctivitis, asthma, and anaphylaxis) result from events occurring after crosslinking of cell-bound IgE by per se innocuous environmental antigens. The frequently raised hypothesis that autosensitization can also be a pathogenetic factor in atopy, gained support by our recent demonstration of IgE antibodies against human proteins in atopic dermatitis patients. To unravel the molecular nature of IgE-defined autoantigens, we used serum IgE from atopic dermatitis patients to screen a human epithelial cDNA expression library. One of the cDNA-encoding IgE-reactive products contained 1501 bp of a 2274 bp open-reading frame finally identified by sequence analysis of two additional cDNA clones resulting from oligonucleotide screening. The IgE-defined autoantigen, designated Hom s 1, exhibited an almost complete sequence identity with a recently described antigen recognized by cytotoxic T cells of a squamous cell carcinoma patient. Purified recombinant Hom s 1 specifically bound IgE from patients with severe atopy. When used as immunogen in rabbits, recombinant Hom s 1 gave rise to an anti-serum that reacted with a cytoplasmic protein exhibiting a broad cellular and tissue reactivity (skin, lung >> gastrointestinal tract >> muscle, brain) and identified a 55 kDa protein in blotted serum IgE preparations. The attractive possibility remains that the Hom s 1-triggered IgE response contributes to the events resulting in allergic tissue inflammation. If so, the respective recombinant molecule may serve as a paradigmatic tool for the diagnosis and treatment of patients with "intrinsic" atopy.

Persistent pruritus after hydroxyethyl starch infusion therapy: a result of long-term storage in cutaneous nerves

A high incidence of severe pruritus has been observed after the administration of hydroxyethyl starch (HES) on account of plasma volume substitution and improvement of the microcirculation. The aim of this study was to elucidate the possible pathomechanisms of HES-induced itching. Skin biopsies were taken from 93 patients, half of them presenting with pruritus, who received HES of various preparations and cumulative dosages. The samples were subjected to immunoelectron microscopical investigation using an antibody highly specific for HES. After infusion therapy with HES, formation of intracytoplasmic storage vacuoles in the skin could be demonstrated in all patients. A dose-dependent uptake of HES was first detectable in macrophages and, thereafter, in endothelial and epithelial cells. Consecutive control biopsies taken from single patients revealed a subsequent reduction of the vacuoles, in size and number, within 3 years, thus indicating a regular cutaneous metabolism of HES. Patients suffering from pruritus consistently showed additional deposition of HES in small peripheral nerves. HES-reactive vacuoles could be demonstrated in the Schwann cells of unmyelinated, as well as small myelinated, nerve fibres, and in endoneural and perineural cells. Neural devacuolization paralleled the clinical improvement in the symptoms. In conclusion, HES deposits in cutaneous nerves, as a consequence of a higher cumulative dosage, may account for the itching seen after HES infusion.

Effects of P. aeruginosa-derived bacterial products on tracheal ciliary function: role of O2 radicals

The purpose of this investigation was to evaluate the effects of bacterial products derived from Pseudomonas aeruginosa on the function of airway cilia and to assess the role of phagocytes and oxygen radicals in the observed responses. Ciliary beat frequency (CBF) was measured in a perfusion chamber with a microscopic technique using tracheal epithelial cells obtained from normal sheep by brush biopsy (70% epithelial cells, 18% macrophages, 11% neutrophils). Baseline CBF ranged between 678 and 1,126 min-1. After 20 min of perfusion with the cell free supernatant of P. aeruginosa culture (mucoid strain), a concentration-dependent depression of CBF was observed with a 58% inhibition at a 1:1 dilution (P less than 0.05). The P. aeruginosa-derived products pyocyanin and 1-hydroxyphenazine also decreased CBF in a dose-related fashion. The cilion-inhibitory effects of the supernatant and bacterial products were markedly attenuated after centrifugation of the brush preparation (80% epithelial cells, 16.5% macrophages, 3.5% neutrophils). Glucose/glucose oxidase also caused a rapid, concentration-dependent cilioinhibition or ciliostasis. Catalase blocked or attenuated the ciliary effects of the supernatant, bacterial products and glucose/glucose oxidase. Thus bacterial products released from P. aeruginosa impaired ciliary activity by a pathway which involved neutrophils and was mediated by toxic oxygen radicals.

Effects of chemical mediators of anaphylaxis on ciliary function

We assessed the effects of selected chemical mediators of anaphylaxis on CBF in vitro. Ciliated epithelial cells were obtained from the trachea of conscious sheep with a cytology brush and suspended in a perfusion chamber containing KH. Ciliary activity was viewed microscopically and recorded on videotape for subsequent slow-motion analysis of CBF. Prostaglandin E1 (10(-8) M to 10(-6) M), prostaglandin E2 (10(-10) M to 10(-6) M), and leukotriene-C4 (10(-8) M) increased CBF between 7% and 33%. Histamine caused ciliostimulation only at the relatively high concentrations above 10(-5) M (7% increase in CBF), whereas prostaglandin F2 alpha (10(-10) M and 10(-6) M) was without effect. In no preparation was ciliary discoordination observed. These findings indicate that several chemical mediators of anaphylaxis stimulate CBF and that the previously described impairment of mucociliary transport in stable allergic asthma or antigen-induced bronchoconstriction is probably not caused by a primary alteration of ciliary function.