The effect of baking and digestion on the allergenicity of wheat flour proteins has been studied. Pooled sera of patients suffering from food allergy to wheat products were tested for IgE binding to ...the proteins of the wheat dough and of the bread crumb and crust, before and after being in vitro digested. During in vitro digestion, the IgE binding protein components of the unheated dough tended to disappear, whereas a permanence of IgE recognition was evident for both the bread crumb and crust. This indicates that the baking process increases the resistance of the potential allergens of the wheat flour to proteolytic digestion, allowing them to reach the gastrointestinal tract, where they can elicit the immunological response. Therefore, the effects of baking must be carefully considered in studying food allergies to wheat products. Keywords: allergy, bread, baking, digestion, food processing, wheat proteins
ABSTRACT
Background. Helicobacter pylori is thought to be involved in atrophic body gastritis. We explored the prevalence of H. pylori infection in asymptomatic subjects with gastric parietal cell ...antibodies, as well as in patients with pernicious anemia, to evaluate a possible role of H. pylori gastric infection in gastric autoimmunity.
Patients and Methods. We studied 79 consecutive asymptomatic subjects with parietal cell antibodies, 24 patients with pernicious anemia, and 66 parietal cell antibody‐negative controls. All patients underwent gastric biopsies for histology and detection of H. pylori. Red blood cell count and volume, serum levels of gastrin, pepsinogen I, iron, folic acid, vitamin B12, and circulating antibodies to H. pylori and to intrinsic factor were also determined.
Results. We found an atrophic body gastritis in 14 of the 79 asymptomatic subjects with parietal cell antibodies (18%) and in 2 of the 66 controls (3%) (p = .01). Mean levels of gastrin were increased (p < .0001), while those of pepsinogen were reduced (p < .001) compared with controls. H. pylori was identified at the gastric level and/or circulating anti‐H. pylori antibodies were detected in 46 parietal cell antibody‐positive subjects (58%) compared with 26 controls (39%) (p = .03). In patients with pernicious anemia we found an atrophic body gastritis in 18 of 24 cases (75%) (p < .001 vs. controls). Mean levels of gastrin were markedly increased (p < .0001) and those of pepsinogen I decreased (p < .0001) relative to controls. Only five of these patients (21%) had evidence of H. pylori infection compared with 46 of the parietal cell antibody‐positive subjects (58%) (p = .003) and 26 of the controls (39%). Considering all patients with gastric autoimmunity (i.e. with parietal cell antibodies and/or with pernicious anemia), H. pylori was found in 44 of 72 of those without atrophy (61%) but in 6 of 31 with gastric body atrophy (19%) (p < .001), indicating that H. pylori infection is greatly reduced when gastric acid secretion decreases.
Conclusions. The frequent detection of H. pylori infection in subjects with early gastric autoimmunity, indicated by the presence of parietal cell antibodies, suggests that H. pylori could have a crucial role in the induction and/or the maintenance of autoimmunity at the gastric level.
Background The involvement of IgE‐mediated hypersensitivity reactions in the genesis of gastrointestinal symptoms after ingestion of foods containing wheat has been rarely reported.
Objective To ...detect IgE specifically binding to wheat proteins in the sera of atopic and non‐atopic patients suffering from gastrointestinal symptoms after ingestion of wheat and to evaluate the reliability of skin prick test and CAP in the diagnosis of food allergy to wheat.
Methods The sera of patients (10 atopic and 10 non‐atopic) previously diagnosed as suffering from irritable bowel syndrome and complaining of symptoms after wheat ingestion were analysed by immunoblotting for IgE binding to water/salt‐soluble and insoluble wheat flour proteins.
Results All the atopic patients and only one of the non‐atopic patients were positive to wheat CAP. For the patients tested, skin prick test was positive for all the atopic patients and for only one of the non‐atopic patients. However, immunoblotting experiments showed the presence of specific IgE to wheat proteins in all the patients. Ten out of 11 of the wheat CAP‐positive patients had IgE binding to a soluble 16‐kDa band, but the same band was recognized, in a slighter way, by only two out of nine of the wheat CAP‐negative patients. Moreover, although almost all of the patients were negative in CAP testing with gluten, 19 out of 20 recognized protein bands belonging to the prolamin fraction.
Conclusions For the atopic patients the positivity to skin prick test and CAP to wheat was in accordance with the immunoblotting results and a food allergy to wheat could be diagnosed. In these patients a major allergen was a 16‐kDa band corresponding to members of the cereal α‐amylase/trypsin inhibitors protein family, the major allergens involved in baker's asthma. In the non‐atopic patients the positive immunoblotting results contrasted with the responses of the allergologic tests, indicating that the allergenic wheat protein preparations currently used are of limited value in detecting specific IgE to wheat and that the fraction of irritable bowel syndrome (IBS) patients with food allergy may be larger than believed.
