Epicutaneous immunogenicity of partially hydrolyzed whey protein evaluated using tape-stripped mouse model.

BACKGROUND: Hydrolyzed cow's milk protein formulas are widely used for infants with a history or risk of cow's milk allergy. Based on the current theory that food allergen sensitization occurs via the skin, we investigated the epicutaneous immunogenicity of partially hydrolyzed whey proteins, which are ingredients in infant formulas. METHODS: BALB/c mice were exposed epicutaneously to whey protein concentrate (WPC) or partial whey protein hydrolysates (PWH1 or PWH2) on tape-stripped skin. Sensitization was assessed by evaluating serum ß-lactoglobulin (ß-LG)-specific antibodies, basophil activation, and cytokine production from ß-LG-stimulated lymphoid cells. The anaphylaxis reaction was evaluated by measuring the rectal temperature and plasma level of mouse mast cell protease-1 after oral ß-LG challenge. Immune cell accumulation in the skin was also analyzed. RESULTS: Substantive sensitization and ß-LG-induced anaphylaxis reaction were observed in WPC-exposed mice, whereas no significant changes were observed in PWH1- or PWH2-exposed mice. The basophil and eosinophil counts increased in WPC-exposed murine skin, not but in PWH1- or PWH2-exposed mice. CONCLUSION: The epicutaneous immunogenicity of PWH1 and PWH2 is markedly decreased, which may reduce the risk of allergen sensitization. Further studies are required to investigate the clinical value of these partial hydrolysates for high-risk infants.

Effects of a diet containing dried grape pomace on blood metabolites and milk composition of dairy cows.

BACKGROUND: The effect of a diet containing 15% grape pomace (GP) on the general health status and milk quality of dairy cows was assessed by plasma biochemistry and total polyphenol (TP) content, milk polyphenols, milk composition and milk protein fractions. RESULTS: Among the polyphenols measured by liquid chromatography-mass spectroscopy in GP, in feed containing GP (GP+) or not containing GP (GP-), gallic acid and epicatechin were present in the highest concentrations (67.58 and 19.23 µg mL-1 , respectively). Higher amounts of TP were also detected in the blood plasma of GP+ cows (114.06 and 83.93 mg GAE L-1 , respectively) but not in their milk (233.17 and 245.75 mg GAE L-1 , respectively). Also a significant increase was found for lactose and ß-lactoglobulin, although there was no effect on α-lactalbumin, albumin, secretory components and caseins. CONCLUSION: Inclusion of 15% GP in the diets of dairy cows is beneficial for overall normal blood constituent metabolism and helps to maintain cow health. The milk of cows fed with a GP diet preserves the normal levels of fat, protein and caseins, and has increased levels of components that make this milk a versatile ingredient material for the food industry (e.g. model whey powders, stability of lactose-rich powders). © 2016 Society of Chemical Industry.

The interaction of platinum-based drugs with native biologically relevant proteins.

This study focuses on the identification of the products that are formed upon binding of therapeutically relevant platinum complexes to proteins like ß-lactoglobulin A (LGA), human serum albumin (HSA), or human hemoglobin (HB). The respective proteins were incubated with the platinum-based anticancer drugs cisplatin, carboplatin, and oxaliplatin. LGA was selected as the model protein in addition to the two most abundant blood proteins HSA and HB. In case of the model protein, the effect of free thiol groups on the affinity of cisplatin, carboplatin, and oxaliplatin was investigated by means of liquid chromatography electrospray ionization time-of-flight mass spectrometry (LC/ESI-ToF-MS). The reduced form of LGA, which contains four free thiol groups more than the native LGA, shows a much higher affinity to the platinum-based drugs. By means of liquid chromatography coupled to inductively coupled plasma mass spectrometry, the reaction behavior of the platinum-based drugs towards HSA and HB was investigated under different conditions considering the chloride concentration (4 or 100 mM) and the incubation time (24 and 48 h). In case of carboplatin, less than 6 % protein-bound platinum was detected. However, both cisplatin and oxaliplatin display a high affinity to the proteins investigated. Further information was obtained by means of LC/ESI-ToF-MS. In case of oxaliplatin, the complex [Pt(DACH)](2+) (DACH=C(6)N(2)H(14)) was identified interacting with HSA and HB. For cisplatin, different results were observed for the two proteins. The complex [Pt(NH(3))(2)Cl](+) interacted predominantly with HSA and [Pt(NH(3))(2)](2+) with HB.

Tolerability of donkey's milk in 92 highly-problematic cow's milk allergic children.

OBJECTIVE: Not exclusively breastfed children with cow's milk allergy (CMA) require a formula or other alternative food, but past and present guidelines differ concerning the best choice. Our aim was to investigate the clinical tolerability, palatability and nutritional adequacy of donkey's milk (DM) in children with proven CMA. It was important to identify a CM replacement for these children, highly problematic from the feeding standpoint, in spite of their age. STUDY DESIGN: A prospective study was conducted on 92 children with CMA, diagnosed through a CM elimination diet, followed by double-blind, placebo-controlled food challenge (DBPCFC) unless contraindicated. Maternal milk was unavailable and current CM substitutes could not be used. Moreover, 89 percent were affected by multiple FA, and subjected to very restricted diets. Within 3 months after the last CM challenge, DBPCFC for DM was performed. CM or DM skin prick test and sIgE determination preceded the CM or DM challenge, respectively. Native electrophoresis and immunoblotting were used to identify CM and DM cross-reactive proteins. Z-scores of weight and length/stature for age were calculated at DM food challenge (T0) and during DM assumption. RESULTS: 83 children (90.2 percent) liked and tolerated DM, at challenge and during follow-up, with increased Z-score for weight and length/stature and improved nutritional parameters. Bovine beta-lactoglobulin was identified as the cross-reacting protein among the DM allergic patients. CONCLUSIONS: DM was found to be a valid alternative foodstuff, in terms of clinical tolerability, palatability and nutritional adequacy, in subjects with CMA who were highly problematic from the feeding standpoint.

Oral administration of fermented red ginseng suppressed ovalbumin-induced allergic responses in female BALB/c mice.

Anti-allergic efficacy of red ginseng (RG) and fermented red ginseng (FRG) was evaluated. RG or FRG were administered to ovalbumin (OVA)-sensitized mice for 8 weeks. Immunoglobulins (Igs), Th1/Th2 type cytokines, and ß-lactoglobulin (BLG) in serum, and intestinal barrier-related molecules in jejunum were measured using enzyme-linked immunosorbent assay or reverse transcription-polymerase chain reaction. Mice sensitized with OVA increased serum IgG1, IgE, OVA-IgG1, and OVA-IgE. Both RG and FRG decreased serum IgE, OVA-IgE, and pro-inflammatory cytokines. Serum BLG, a marker of gut permeability, was significantly higher in sensitized animals and was decreased in mice fed RG or FRG. In addition, intestinal barrier-related markers such as MMCP-1, IL-4, TNF-α, COX-2, and iNOS mRNA expressions were decreased by RG or FRG. Our results suggest in vivo anti-allergic activities of RG or FRG, which are associated with the regulation of Th1/Th2 balance, intestinal inflammation and subsequent the suppression of IgE.

Effect of extensively hydrolyzed milk formula on growth and resistance to bronchitis and atopic dermatitis in infants and toddlers.

OBJECTIVE: This study aimed to evaluate the adverse effects of extensively hydrolyzed milk formula on growth in infants and toddlers. METHODS: Prospectively, 45 infants and toddlers with a positive history of cow's milk allergy confirmed by positive skin prick test and high IgE levels for either alpha-lactalbumin, beta-lactoglobulin, or casein and positive single-blind food challenge received extensively hydrolyzed milk formulas for 1 year. Sex-normalized percentiles of heights and weights of infants and toddlers before their enrollment in the study were compared to those at the end of the study. The contribution of breastfeeding, early use of bottle feeding and intake of adapted or special milk formulas, and history of bronchitis and atopic dermatitis on toddlers' growth were also evaluated by multivariate analysis. RESULTS: Similar percentiles of the children's weight and height were observed at the beginning of the study and 1 year later. According to the multivariate analysis, sex, breastfeeding, early bottle feeding, ingestion of adapted or special milk formulas, atopic dermatitis, and bronchitis were not correlated with either the children's weight or height at diagnosis of the allergy or at 1 year of follow-up (P > .10). Weights and heights were not different between toddlers who had atopic dermatitis or bronchitis during the study period and those who did not. CONCLUSIONS: Growth of infants and toddlers with cow's milk allergy was not affected by the intake of extensively hydrolyzed milk for 1 year. Atopic dermatitis and bronchitis did not appear to have any deleterious effect on these children's growth.

The effects of exclusion of dietary egg and milk in the management of asthmatic children: a pilot study.

Current understanding of the use of exclusion diets in the management of asthma in children is limited and controversial. The aim of this study was to examine the effects of excluding eggs and milk on the occurrence of symptoms in children with asthma and involved 22 children aged between three and 14 years clinically diagnosed as having mild to moderate disease. The investigation was single blind and prospective, and parents were given the option of volunteering to join the 'experiment' group, avoiding eggs, milk and their products for eight weeks, or the 'control' group, who consumed their customary food. Thirteen children were recruited to the experimental group and nine to the control group. A trained paediatrician at the beginning and end of the study period assessed the children. A seven-day assessment of food intake was made before, during and immediately after the period of dietary intervention in both groups. A blood sample was taken from each child for determination of food specific antibodies and in those children who could do so, the peak expiratory flow rate (PEFR) was measured. Based on the recommended nutrient intake (RNI), the mean percentage energy intake of the children in the experimental group was significantly lower (p < 0.05) in the experimental group. After the eight-week study period and compared with baseline values, the mean serum anti-ovalbumin IgG and anti-beta lactoglobulin IgG concentrations were statistically significantly reduced (p < 0.05) for both in the experimental group. In contrast, the values for anti-ovalbumin IgG in the control group were significantly increased and those for anti-beta lactoglobulin IgG were practically unchanged. The total IgE values were unchanged in both groups. Over the study period, the PEFR in those children in the experimental group able to perform the test was significantly increased, but no such change was noted in the children in the control group who could do the test. These results suggest that even over the short time period of eight weeks, an egg- and milk-free diet can reduce atopic symptoms and improve lung function in asthmatic children.

Maternally delivered nutritive allergens in cord blood and in placental tissue of term and preterm neonates.

BACKGROUND: The proliferation of cord blood mononuclear cells in response to nutritive and inhalant allergens implies intrauterine exposure with resulting T cell priming. However, the mechanisms triggering these fetal allergen-specific immune responses are incompletely understood. METHODS: We studied the placental release of endogenous beta-lactoglobulin (BLG) and ovalbumin (OVA) by the use of an open ex vivo placental perfusion model. Preterm and term placentas were obtained immediately after delivery to recover functionally active fetal and maternal circulations. Fetal and maternal perfusate samples were collected throughout the perfusion experiments with medium. Matched cord blood samples were collected separately. All samples were tested for the presence of OVA and BLG by allergen-specific ELISAs. RESULTS: In 16 out of 19 placentas, the nutritive allergens could be detected both in fetal and maternal perfusate samples. Fetal wash out levels of the allergens BLG and OVA from the placental tissue of preterm and term deliveries were observed in traces and up to 44.4 and 2.6 ng/mL, respectively. In cord blood of preterm and term neonates, BLG and OVA could be detected at concentrations up to 16.7 and 5 ng/mL, respectively. CONCLUSION: These findings provide direct evidence for the release of tiny amounts of nutritive allergens from placental tissue indicating diaplacental allergen transfer and fetal exposure to nutritive allergens in vivo.

Further evidence regarding the effect of dietary protein on oral tolerance against beta-lactoglobulin through Th1-mediated immune response in mice.

Oral tolerance is a potential strategy for preventing or minimizing aberrant immune responses. Although, oral tolerance has been extensively studied, to date the effects of dietary protein on the induction of oral tolerance are poorly understood. We have previously shown that restricted dietary protein induces oral tolerance to ovalbumin. This study was designed to investigate whether or not such tolerance occurs with beta-lactoglobulin (BLG) instead of ovalbumin (OVA) and if the tolerance resulting from this feeding regimen involves Th1-mediated immune response. Female BALB/c mice fed either 20% or 5% dietary protein were given 5 mg BLG or water orally for four consecutive days and then immunized intraperitoneally (ip) twice with BLG at 3-wk intervals. Oral tolerance induction was compared in BLG-fed and water-fed mice by measuring total IgE, BLG-specific antibodies, footpad reactions, splenocyte proliferation, and cytokine production. When mice were given BLG orally before ip immunization, the Th1-mediated immune responses (production of IL-2, IFN-gamma, and IgG2a) were significantly reduced, whereas the Th2-mediated immune responses (production of IL-4 and IgG1) were unchanged. The Th1-mediated immune responses were markedly down-regulated in mice fed 5% protein as compared to those in mice fed 20% protein. Moreover, the production of total IgE, BLG-specific IgE, splenocyte proliferation, and footpad reactions were more reduced in mice fed 5% protein than those in mice fed 20% protein. The present study provides evidence that dietary protein plays an important role in the induction of oral tolerance against BLG as the result of, clear down-regulation of Th1 helper activity accompanied by a reduction in IgE.

A vegan diet free of gluten improves the signs and symptoms of rheumatoid arthritis: the effects on arthritis correlate with a reduction in antibodies to food antigens.

OBJECTIVE: Whether food intake can modify the course of rheumatoid arthritis (RA) is an issue of continued scientific and public interest. However, data from controlled clinical trials are sparse. We thus decided to study the clinical effects of a vegan diet free of gluten in RA and to quantify the levels of antibodies to key food antigens not present in the vegan diet. METHODS: Sixty-six patients with active RA were randomized to either a vegan diet free of gluten (38 patients) or a well-balanced non-vegan diet (28 patients) for 1 yr. All patients were instructed and followed-up in the same manner. They were analysed at baseline and after 3, 6 and 12 months, according to the response criteria of the American College of Rheumatology (ACR). Furthermore, levels of antibodies against gliadin and beta-lactoglobulin were assessed and radiographs of the hands and feet were performed. RESULTS: Twenty-two patients in the vegan group and 25 patients in the non-vegan diet group completed 9 months or more on the diet regimens. Of these diet completers, 40.5% (nine patients) in the vegan group fulfilled the ACR20 improvement criteria compared with 4% (one patient) in the non-vegan group. Corresponding figures for the intention to treat populations were 34.3 and 3.8%, respectively. The immunoglobulin G (IgG) antibody levels against gliadin and beta-lactoglobulin decreased in the responder subgroup in the vegan diet-treated patients, but not in the other analysed groups. No retardation of radiological destruction was apparent in any of the groups. CONCLUSION: The data provide evidence that dietary modification may be of clinical benefit for certain RA patients, and that this benefit may be related to a reduction in immunoreactivity to food antigens eliminated by the change in diet.

Time course of changes in the intestinal permeability of food-sensitized rats after oral allergen challenge.

Rats were sensitized with ovalbumin (OVA) with a molecular weight of 45 kd, challenged with OVA orally, followed by orally administered beta-lactoglobulin (BLG) as an intestinal permeability marker. BLG is a macro-molecular protein with a molecular weight of 18 kd. Blood BLG concentrations were measured (by ELISA) serially over 4 hours following BLG administration, which in turn was given 1 hour after OVA challenges. The maximum BLG concentration was at 2 hours. BLG was then administered orally 1, 3, 6, 12 and 24 hours after oral OVA challenge, and the serum BLG concentration at 2 hours after BLG administration was compared among the five groups. BLG appeared in the circulation of the animals 1, 6 and 24 hours after allergen challenge, but not after 3 and 12 hours. The serum BLG concentration was not significantly different at 1, 6 and 24 hours. Histopathological examinations of the intestines showed mast cell infiltration of the intestinal mucosa at 1 hour, remarkable edema of villi at 3 hours, eosinophil infiltration at 6 hours, an increase of goblet cells at 12 hours and villous atrophy and lymphocyte infiltration at 24 hours. The appearance in the serum of three BLG peaks of comparable heights suggested that the intestinal absorption of BLG may be related to a late and delayed phase as well as the immediate IgE-dependent phase response.

Effect of whey hydrolysate formula on the transfer of beta-lactoglobulin into serum and milk in mice.

This study was performed to elucidate the effect of whey hydrolysate formula on the transfer of an antigen into serum and milk. The concentrations of beta-lactoglobulin in serum and milk were positively correlated (p < 0.01). The concentration of beta-lactoglobulin in serum tended to become low in the mouse and to be accompanied with a high level of fecal anti-beta-lactoglobulin IgA concentration. The fecal anti-beta-lactoglobulin IgA of mice fed hydrolysate formula for 12 weeks was significantly higher than that of the control formula-fed mice (p < 0.05). These results suggest that a high level of intestinal IgA elicited by the feeding of hydrolysate formula may reduce the transfer of beta-lactoglobulin into serum and milk.

Effect of saponin on the transmucosal passage of beta-lactoglobulin across the proximal small intestine of normal and beta-lactoglobulin-sensitised rats.

The ability of saponins and glycoalkaloids to permeabilise the mammalian intestinal barrier has been previously demonstrated in vitro, leading to the hypothesis that membranolytic saponins may facilitate transfer to the tissues of otherwise excluded macromolecules. An enhanced uptake of, for instance, potentially allergenic species from the lumen is one of the factors that may affect the induction of food allergy, and its presentation in already sensitised individuals. In the experiments described here, an increase in the transmucosal uptake of the milk allergen beta-lactoglobulin (beta LG) was assessed in non-sensitised and sensitised Brown Norway rats in the presence of Gypsophila saponin. Isolated jejunal loops were exposed in vivo to either beta LG followed by saponin, saponin followed by beta LG or the two compounds simultaneously. Portal vein blood samples were collected and assayed for beta LG and rat mucosal mast cell protease (RCMP II) activity. Mucosal tissue was also examined histologically and assayed for histamine content. Sham-operated animals, exposed to physiological buffer alone, were included as controls and beta LG measurements corrected for this component which was negligible. No transfer of beta LG occurred in the absence of saponin in non-sensitised rats, whereas a significant enhancement was observed in the presence of saponin. beta LG was detected in the portal circulation of sensitised rats exposed to beta LG alone; however addition of saponin to the intestinal lumen further enhanced this uptake, possibly by an independent mechanism. Histological examination of the mucosal epithelium exposed to saponin revealed damage, especially at the villus tips. Mucosal histamine and serum RCMP II concentrations were consistent with the differences observed between sensitised and non-sensitised animals. It is concluded that exposure to food constituents capable of permeabilising the mucosal epithelium may increase the risk of sensitisation to dietary antigens.

Dietary nucleotides might influence the humoral immune response against cow's milk proteins in preterm neonates.

The objective of this study was to evaluate the influence of dietary nucleotide supplementation in preterm infants during the first month of life on the intestinal permeability to lactulose, mannitol and to beta-lactoglobulin and on the development of circulating antibodies to beta-lactoglobulin and alpha-casein. Twenty-seven preterm infants were enrolled in the study; 11 of them were fed a standard low-birth weight milk formula and 16 infants were fed the same formula supplemented with nucleotides at similar levels to those found in human milk. Blood and urine samples were obtained at 1, 7 and 30 days of age. Serum beta-lactoglobulin, serum IgG antibody to alpha-casein and serum IgG antibody to beta-lactoglobulin were measured by ELISA. The lactulose/mannitol urinary excretion rate was measured by gas liquid chromatography. Neither the intestinal permeability to saccharides nor the intestinal absorption of beta-lactoglobulin were affected by the nucleotide supplementation. However, serum concentrations of IgG antibody to beta-lactoglobulin were higher in preterm neonates fed the supplemented formula than in those fed the standard formula. According to these results, dietary nucleotides might influence the maturation of the humoral immune response in preterm newborn infants.

Gastroesophageal reflux associated with cow's milk allergy in infants: which diagnostic examinations are useful?

Gastroesophageal reflux (GER) in infants can be secondary to food allergy. We have evaluated the frequency with which GER is associated with cow's milk protein allergy (CMPA) in infants < 1 yr old and tried to indicate the laboratory and instrumental examinations useful in diagnosing GER + CMPA. We studied 140 infants (60 M, 80 F), mean age 6.0 +/- 2.8 months. After 24-h esophageal pH-metry, esophageal endoscopy, and elimination diet, followed by a double-blind challenge, the patients were divided into four groups: primary GER, GER secondary to CMPA, CMPA without GER, and a control group with subjects suffering from neither GER nor CMPA. Thirty of 72 patients with GER were also suffering from CMPA. No differences were observed as regards age, sex, symptoms, and clinical or family history between patients with GER only and those with GER + CMPA. The immunological test most useful for GER + CMPA diagnosis was the IgG anti-beta-lactoglobulin assay: positive in 27/30 subjects with GER + CMPA and in 4/42 patients with GER only. We also observed a characteristic pattern of the pH-monitoring tracing in 26/30 patients with GER + CMPA but in none of the 42 patients with GER only. This consisted of a progressive, constant reduction in esophageal pH at the end of a feed, which continued up to the following feed, when pH rose steeply. We conclude that the evidence of this characteristic tracing and of a high IgG anti-beta-lactoglobulin value are specific and sensitive tests for GER + CMPA diagnosis.

Effects of native and hydrolyzed whey protein on intestinal repair of severely starved rats at weaning.

The aim of this study was to evaluate the effect of two sources of dietary nitrogen (isolated whey protein and hydrolyzed whey protein) on the intestinal repair of malnourished rats at weaning. The malnutrition was achieved by a 3 days' starvation period. Normally fed male Wistar rats were used as controls. Intestinal repair was studied after a refeeding period of 4 days. The parameters studied included nitrogen balance, lactase, sucrase, isomaltase, and maltase activities of the jejunum; liver acetylcholinesterase and glutamate dehydrogenase activities; and the serum amino acid profile. In addition, tests of intestinal permeability to macromolecules were performed by measurement of ovalbumin and beta-lactoglobulin in serum. Both diets of led to the recovery of the severely starved rats, in terms of the values of all the parameters evaluated. The serum beta-lactoglobulin was the only exception, because its concentration was significantly lower in the normally fed animals. This study suggests that the intestinal mucosal barrier is not completely repaired, even after a 4-day refeeding period, to the point of being suitable to accept an increase in the uptake of antigens.

Prediction of milk yields from serum beta-lactoglobulin concentrations in pregnant heifers.

The serum concentration of beta-LG at wk 26 of pregnancy was determined in Holstein heifers of known genetic merit to evaluate use of a single blood sample as an index to predict their subsequent milk yield. Concentrations of beta-LG varied widely (16 to 1200 ng/ml) in the serum of the heifers at this stage of pregnancy. Subsequent measures of lactation performance showed that heifers with high beta-LG concentrations in pregnancy produced more milk than those with low beta-LG in serum. Previous studies have shown that the concentration of beta-LG in serum shows a log-linear increase during pregnancy, which is consistent with correlation to the growth of the mammary parenchyma. Therefore, the logarithm beta-LG concentration was used as the index in this study. The correlations of this index were .46, .54, and .48 for first lactation 305-d yields of milk, fat, and protein, respectively. The results suggest that serum concentrations of beta-LG estimated from a single blood sample at this stage of pregnancy can be used to predict milk yield. Analysis showed that an explanation of future milk yield was significantly improved by use of serum beta-LG and parent average. Serum beta-LG can be used as a physiological marker to prescreen heifers for lactation potential.

Chronic constipation as a symptom of cow milk allergy.

Twenty-seven consecutive infants (mean age, 20.6 months) with chronic "idiopathic" constipation were studied to investigate the possible relation between constipation and cow milk protein allergy (CMPA). The infants were initially observed on an unrestricted diet, and the number of stools per day was recorded. Subsequently the infants were put on a diet free of cow milk protein (CMP) for two periods of 1 month each, separated by two challenges with CMP. During the CMP-free diet, there was a resolution of symptoms in 21 patients; during the two consecutive challenges, constipation reappeared within 48 to 72 hours. In another six patients the CMP-free diet did not lead to improvement of constipation. Only four of the patients who improved on the CMP-free diet had concomitant symptoms of suspected CMPA, but a medical history of CMPA was found in 15 of the 21 patients cured and in only one of the six patients whose condition had not improved (p < 0.05); in addition, in 15 of the 21 cured patients, results of one or more laboratory tests (specific IgE, IgG, anti-beta-lactoglobulin, circulating eosinophils) were positive at the time of diagnosis, indicating hypersensitivity, compared with one of the six patients whose condition did not improve (p < 0.05). The endoscopic and histologic findings at the time of diagnosis showed proctitis with monocytic infiltration in two patients cured with the CMP-free diet; after 1 month on this diet, they were completely normal. We conclude that constipation in infants may have an allergic pathogenesis.

Human alpha-lactalbumin and bovine beta-lactoglobulin absorption in infants.

We investigated gut permeability to human alpha-lactalbumin (ALA) and bovine beta-lactoglobulin (BLG) in 20 infants from birth to 8 months or until weaning, before which they were on a strictly cow's-milk-free diet. We measured the proteins with a sensitive, solid-phase, double-sandwich immunofluorometric assay. Median (range) levels of serum ALA on days 3-4 after birth, and at 1 and 2 months of age were 31 (12-225), 6 (0-55), and 2 (0-16) micrograms/l serum per g ALA given per kg body weight, respectively. At 3, 5, and 8 months of age, only trace amounts of ALA were found. One week after weaning, serum BLG was found in 5/13 infants (38%) and at 2 weeks in 3/14 infants (21%), with median concentrations of 7 and 4 micrograms/l serum per g BLG given per kg body weight, respectively. No ALA could be detected in any of these samples. In absorption of ALA, the four infants who had allergic symptoms did not differ from those without symptoms. Thus, systemic absorption of ALA and BLG does occur in infants. Absorption of ALA is greatest after birth, when 3 x 10(-4) (median) of the given antigens are absorbed, but absorption decreases rapidly. The gut may often be transiently permeable to BLG when cow's-milk-based formula is started.