Effect of heat treatment on milk and egg proteins allergenicity.

BACKGROUND: Heating destroys many conformational epitopes and reduces allergenicity of some foods. IgE-epitope binding has been shown to be different among patients who outgrew their cow's milk or hen's egg allergy and those who did not. A significant proportion of milk- or egg-allergic children are tolerant to these foods in their baked forms. We sought to explore the effects of heating on milk and egg proteins and to evaluate for differences in immunolabeling among children with regard to reactivity to heated milk or egg. METHODS: Sera from participants in clinical dietary intervention trials were utilized. Milk and egg samples were variably heated and prepared (at times within a wheat matrix). Sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), protein transfer, and Western blot were completed. RESULTS: Sera from 20 milk-allergic and 24 egg-allergic children were utilized. Gel electrophoresis showed strongly staining casein bands that persisted for up to 60 min of heating. In contrast, ß-lactoglobulin and α-lactalbumin bands became progressively weaker with increasing heating times, with no detectable ß-lactoglobulin after 15-20 min of heating. The ovalbumin band became progressively weaker, whereas ovomucoid remained stable after 25 min of heating. Immunolabeling revealed that all heated milk-reactive children possessed IgE antibodies that bound the casein fraction regardless of heating time. Presence of wheat during heating resulted in decreased IgE antibody binding to milk and egg white proteins. CONCLUSION: Heating has a different effect on whey and caseins in cow's milk and ovalbumin and ovomucoid in hen's egg white. The effect of heat on protein allergenicity is affected by the temperature and duration, along with the presence of wheat.

Basophil reactivity, wheal size, and immunoglobulin levels distinguish degrees of cow's milk tolerance.

BACKGROUND: In our previous study about 75% of children with cow's milk allergy tolerated baked milk products, which improved their prognosis and quality of life. OBJECTIVE: We sought to identify biomarkers of varying degrees of clinical tolerance among a cohort of children with cow's milk allergy. METHODS: One hundred thirty-two subjects were initially classified as baked milk-reactive, baked milk-tolerant, or having "outgrown milk allergy" based on the results of oral food challenges. The baked milk-tolerant group was then divided into 3 groups based on the amount and degree of heat-denatured milk protein that they could tolerate. Serum was analyzed for allergen-specific IgE and IgG(4) levels, basophil reactivity was assessed in whole blood stimulated with serial 10-fold dilutions of milk protein, and skin prick tests (SPTs) were performed to commercial milk extract. Activated basophils were defined by using flow cytometry as CD63(bright)CD203c(+)CD123(+)HLA-DR(dim/-)CD41a(-)lineage(-). Data were analyzed by using the Jonckheere-Terpstra test. RESULTS: Significant differences across the 5 clinical groups were seen for median casein- and milk-specific IgE levels, casein-specific IgG(4) levels, and casein IgE/IgG(4) ratios; milk-specific to nonspecific basophil activation ratio, median basophil reactivity, and spontaneous basophil activation (CD203c expression after stimulation with RPMI); and milk SPT wheal diameters. Casein- and milk-specific IgE level, milk-specific basophil reactivity, and milk SPT wheal diameter are all significantly greater among patients with milk allergy who react to baked milk than among those who tolerate it. CONCLUSIONS: The majority of patients with milk allergy are able to tolerate some forms of baked milk in their diets. Different phenotypes of children with cow's milk allergy can be distinguished by casein- and milk-specific IgE levels, milk-specific basophil reactivity, and milk SPT mean wheal diameters. Spontaneous basophil activation is greater among patients with more severe clinical milk reactivity.

Tolerance to extensively heated milk in children with cow's milk allergy.

BACKGROUND: Cow's milk allergy is the most common childhood food allergy. Previously we noted that children who outgrew their milk allergy had milk-specific IgE antibodies primarily directed against conformational epitopes; those with persistent milk allergy also had IgE antibodies directed against specific sequential epitopes. OBJECTIVE: Because high temperature largely destroys conformational epitopes, we hypothesized that some children with milk allergy would tolerate extensively heated (baked) milk products. METHODS: Children with milk allergy were challenged with heated milk products; heated milk-tolerant subjects were subsequently challenged with unheated milk. Heated milk-tolerant, unheated milk-reactive subjects ingested heated milk products for 3 months and were then re-evaluated. Immune responses were assessed in all subjects; growth and intestinal permeability were followed in heated milk-tolerant subjects. RESULTS: One hundred children (mean age, 7.5 years; range, 2.1-17.3 years) underwent heated milk challenges. Sixty-eight subjects tolerated extensively heated milk only, 23 reacted to heated milk, and 9 tolerated both heated and unheated milk. Heated milk-reactive subjects had significantly larger skin prick test wheals and higher milk-specific and casein-specific IgE levels than other groups. At 3 months, subjects ingesting heated milk products had significantly smaller skin prick test wheals and higher casein-IgG(4) compared with baseline; other immunologic parameters, growth, and intestinal permeability were not significantly different. Heated milk-reactive subjects had more severe symptoms during heated milk challenge than heated milk-tolerant subjects experienced during their unheated milk challenge. CONCLUSION: The majority (75%) of children with milk allergy tolerate heated milk.

Osteoarticular infectious complications in patients with primary immunodeficiencies.

PURPOSE OF REVIEW: To describe the incidence and management of various infectious arthritides in selected primary immunodeficiency states. RECENT FINDINGS: Joint complications have been a well recognized finding in patients with primary immunodeficiencies for many years. Many are clearly infectious in etiology, but other apparently noninfectious joint abnormalities similar to rheumatoid arthritis have been shown to be due to an underlying infectious trigger. In humoral immunodeficiencies such as common variable immunodeficiency and X-linked agammaglobulinemia, bacterial organisms are the most common causes of infectious arthritis, but mycoplasmas and ureaplasmas are also of particular importance. In nonhumoral immunodeficiencies, noninfectious inflammatory arthritides are more prevalent, although microbiologic organisms have been reported in some cases of arthritis. Lack of appropriate culturing techniques and documentation of infectious agents may underestimate the prevalence of low-virulence infections in these patients. SUMMARY: Infectious arthritis is a significant comorbidity associated with primary immunodeficiencies and can be the presenting feature for some patients. Prompt examination for common as well as atypical organisms is not only important for the treatment but also crucial to the understanding of the exact etiology of arthritides as a whole in these disorders.