Sheep and goat's milk allergy--a case study

Allergen Risk Assessment for Specific Allergy to Small Ruminant's Milk: Development of Sensitive Immunoassays to Detect Goat's and Sheep's Milk Contaminations in Dairy Food Matrices

Despite a high level of sequence identity between cow's, goat's, and sheep's milk (CM, GM, and SM, respectively) proteins, some patients tolerant to CM are allergic to GM and SM. In most cases, this specificity is due to the presence of IgE antibodies that bind only to caprine and ovine caseins. The patients may then develop severe allergic reactions after ingestion of CM products contaminated with low amounts of GM or SM. We thus aimed to develop an assay able to detect traces of caprine/ovine β-caseins in different food matrices, irrespective of the presence of the bovine homolog. We produced monoclonal antibodies (mAbs) specific to caprine caseins in mice tolerized to the bovine whole casein then sensitized to the caprine whole casein. In order to develop a two-site immunometric assay, we selected mAbs that could discriminate the caprine β-casein from its bovine homolog. Characteristics and performances of two tests were determined with various dairy products. Results were analyzed in relation with the IgE-immunoreactivity of the food matrices, thanks to sera from CM, GM/SM allergic patients. Our two-site immunometric assays demonstrated a high sensitivity with a detection limit of 1.6–3.2 ng/mL of caprine and ovine β-caseins. The tests were able to detect contaminations of GM in CM at the ppm level. Heat-treatment, ripening and coagulation processes, usually applied to dairy products that exhibit a very high IgE-immunoreactivity, did not impair the test sensitivity. These quantitative assays could then be useful for the risk assessment of food products potentially contaminated with GM and SM in order to prevent adverse reactions in patients specifically allergic to these milks.

Shellfish Allergy: a Comprehensive Review

Shellfish allergy is of increasing concern, as its prevalence has risen in recent years. Many advances have been made in allergen characterization. B cell epitopes in the major allergen tropomyosin have been characterized. In addition to tropomyosin, arginine kinase, sarcoplasmic calcium-binding protein, and myosin light chain have recently been reported in shellfish. All are proteins that play a role in muscular contraction. Additional allergens such as hemocyanin have also been described. The effect of processing methods on these allergens has been studied, revealing thermal stability and resistance to peptic digestion in some cases. Modifications after Maillard reactions have also been addressed, although in some cases with conflicting results. In recent years, new hypoallergenic molecules have been developed, which constitute a new therapeutic approach to allergic disorders. A recombinant hypoallergenic tropomyosin has been developed, which opens a new avenue in the treatment of shellfish allergy. Cross-reactivity with species that are not closely related is common in shellfish-allergic patients, as many of shellfish allergens are widely distributed panallergens in invertebrates. Cross-reactivity with house dust mites is well known, but other species can also be involved in this phenomenon.

Fresh goat's milk for infants: myths and realities--a review

Many infants are exclusively fed unmodified goat's milk as a result of cultural beliefs as well as exposure to false online information. Anecdotal reports have described a host of morbidities associated with that practice, including severe electrolyte abnormalities, metabolic acidosis, megaloblastic anemia, allergic reactions including life-threatening anaphylactic shock, hemolytic uremic syndrome, and infections. We describe here an infant who was fed raw goat's milk and sustained intracranial infarctions in the setting of severe azotemia and hypernatremia, and we provide a comprehensive review of the consequences associated with this dangerous practice.

Goat's milk allergy

BACKGROUND

Goat's milk (GM) allergy not associated with allergy to cow's milk (CM) is a rare disorder. Caseins have been implicated has the major allergens eliciting symptoms.

METHODS

We report the case of a 27 years-old female patient that experienced two episodes of urticaria related to ingestion of goat's cheese (GC). She tolerated CM, dairy products and sheep cheese. Skin prick tests were performed with GM, CM, bovine casein and alpha -lactalbumin and fresh milk and GC. Serum specific IgE to GM, CM and its fractions, and GM and CM immunobloting assays with inhibition were also evaluated.

RESULTS

Skin tests were positive to GM and GC and negative to CM. GM immunoblot showed an IgE-binding 14 kDa band that was totally inhibited after serum pre-incubation with GM.

CONCLUSIONS

Allergens other than casein can be involved in allergy to GM. Even small quantities of protein can elicit symptoms.

Allergy to goat and sheep milk without allergy to cow's milk

BACKGROUND

Cow's milk (CM) allergy is the most frequent cause of food allergy in infants. Most children who are allergic to CM are also sensitized to whey proteins and/or to the casein fraction and many of them cannot tolerate goat's or sheep's milk (GSM) either. Conversely, the GSM allergies that are not associated with allergic cross-reactivity to CM are rare.

METHODS

Twenty-eight children who had severe allergic reactions, including anaphylaxis, after consumption of GSM products but tolerated CM products were recruited in a retrospective study. Whole casein and whey proteins were fractionated from CM and GSM. beta-Lactoglobulin and the different caseins were isolated, purified and used to perform enzyme allergosorbent tests (EAST) and EAST inhibition studies with the sera of the allergic children.

RESULTS

Clinical observations, skin prick testing and immunoglobulin (Ig)E-binding studies confirmed the diagnosis of GSM allergy without associated CM allergy. EAST determinations demonstrated that GSM allergy involves the casein fraction and not whey proteins. Cow's milk caseins were not at all or poorly recognized by the patient's IgE, while alphaS(1)-, alphaS(2)- and beta-caseins from GSM were recognized with a high specificity and affinity. In all cases, increasing concentrations of CM caseins failed to inhibit the binding of patient's IgE to sheep or goat milk caseins, whereas this binding was completely inhibited by GSM caseins.

CONCLUSIONS

The characteristics of GSM allergy differ from those of the CM allergy because it affects older children and appears later. CM products do not elicit any clinical manifestation in GSM allergic patients, whereas CM allergic patients, usually cross-react to GSM. In all the GSM allergic children, the IgE antibodies recognized the caseins but not the whey proteins. Moreover, IgE specificity and affinity was high to GSM and lower to CM caseins despite their marked sequence homology. Doctors and allergic individuals should be aware that GSM allergy requires a strict avoidance of GSM and milk-derived products because reactions could be severe after ingestion of minimal doses of the offending food.