Research on human milk oligosaccharides (HMOs) has received much attention in recent years. However, it started about a century ago with the observation that oligosaccharides might be growth factors for a so-called bifidus flora in breast-fed infants and extends to the recent finding of cell adhesion molecules in human milk. The latter are involved in inflammatory events recognizing carbohydrate sequences that also can be found in human milk. The similarities between epithelial cell surface carbohydrates and oligosaccharides in human milk strengthen the idea that specific interactions of those oligosaccharides with pathogenic microorganisms do occur preventing the attachment of microbes to epithelial cells. HMOs may act as soluble receptors for different pathogens, thus increasing the resistance of breast-fed infants. However, we need to know more about the metabolism of oligosaccharides in the gastrointestinal tract. How far are oligosaccharides degraded by intestinal enzymes and does oligosaccharide processing (e.g. degradation, synthesis, and elongation of core structures) occur in intestinal epithelial cells? Further research on HMOs is certainly needed to increase our knowledge of infant nutrition as it is affected by complex oligosaccharides.

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Antigen-specific immunotherapy combats autoimmunity or allergy by reinstating immunological tolerance to target antigens without compromising immune function. Optimisation of dosing strategy is critical for effective modulation of pathogenic CD4+ T cell activity. Here we report that dose escalation is imperative for safe, subcutaneous delivery of the high self-antigen doses required for effective tolerance induction and elicits anergic, IL-10-secreting regulatory CD4+ T cells. Analysis of the CD4+ T cell transcriptome, at consecutive stages of escalating dose immunotherapy, reveals progressive suppression of transcripts positively regulating inflammatory effector function and repression of cell cycle pathways. We identify transcription factors, c-Maf and NFIL3, and negative co-stimulatory molecules, LAG-3, TIGIT, PD-1 and TIM-3, which characterise this regulatory CD4+ T cell population and whose expression correlates with the immunoregulatory cytokine IL-10. These results provide a rationale for dose escalation in T cell-directed immunotherapy and reveal novel immunological and transcriptional signatures as surrogate markers of successful immunotherapy.

The skin is an important immunological organ with an outer protective layer, the stratum corneum forming a barrier between the skin-associated lymphoid tissue and the environment. We show that gently removing the stratum corneum with adhesive tape permits potent epicutaneous immunization to protein antigens. IL-4 secretion by T cells from draining lymph nodes and high levels of specific IgE and IgG1 with no IgG2a showed that the immune responses induced following epicutaneous antigen exposure are strongly Th2 biased. Similar responses were obtained with different antigens and mouse strains. In contrast, subcutaneous immunization with antigen delivery into the dermis was less potent and gave predominantly Th1 responses. Removal of the stratum corneum increased expression of MHC class II, CD86, CD40, CD54 and CD11c on Langerhans cells, but did not cause them to migrate. Rapid migration from epidermis to draining lymph node was obtained, however, by exposure to antigen after removal of the stratum corneum, suggesting that maturation and migration of Langerhans cells are independently regulated events. These results suggest that antigen presentation by Langerhans cells gives predominantly Th2 responses. This may provide an explanation for allergic sensitization to some antigens. It may also be a useful non-invasive, non-adjuvant-dependent method of vaccination.

In the absence of clear confirmation or refutation of the results of the earlier study and in an attempt to meet some of the criticisms, we undertook the current study using a similar design, but with improved methodology and clearly defined outcome measures. MethodsChildren were referred by general practitioners, paediatricians, and psychiatrists to a special diet and behaviour clinic set up at the Hospital for Sick Children. All children accepted for the study met DSM III criteria for attention deficit disorder with hyperactivity,10 were between 3 and 12 years old, and had IQs above 70. Where children were already on diets their parents were asked to take them off the diet for a week before the initial interview.

KEYWORDS food allergy • food intolerance • IgG • IgG4 • in vitro tests ABSTRACTSerological tests for immunoglobulin G4 (IgG4) against foods are persistently promoted for the diagnosis of food-induced hypersensitivity. Since many patients believe that their symptoms are related to food ingestion without diagnostic confirmation of a causal relationship, tests for food-specific IgG4 represent a growing market. Testing for blood IgG4 against different foods is performed with large-scale screening for hundreds of food items by enzyme-linked immunosorbent assay-type and radioallergosorbent-type assays in young children, adolescents and adults. However, many serum samples show positive IgG4 results without corresponding clinical symptoms. These findings, combined with the lack of convincing evidence for histamine-releasing properties of IgG4 in humans, and lack of any controlled studies on the diagnostic value of IgG4 testing in food allergy, do not provide any basis for the hypothesis that food-specific IgG4 should be attributed with an effector role in food hypersensitivity. In contrast to the disputed beliefs, IgG4 against foods indicates that the organism has been repeatedly exposed to food components, recognized as foreign proteins by the immune system. Its presence should not be considered as a factor which induces hypersensitivity, but rather as an indicator for immunological tolerance, linked to the activity of regulatory T cells. In conclusion, food-specific IgG4 does not indicate (imminent) food allergy or intolerance, but rather a physiological response of the immune system after exposition to food components. Therefore, testing of IgG4 to foods is considered as irrelevant for the laboratory work-up of food allergy or intolerance and should not be performed in case of food-related complaints. ARTICLE TEXTAn adverse food reaction is a general term describing clinically abnormal responses to an ingested food that might occur secondary to nonallergic food hypersensitivity (food intolerance) or allergic food hypersensitivity (food allergy).Food allergy is an immunologic reaction that involves in particular the immunoglobulin E (IgE) mechanism, of which anaphylaxis is the classic example.Food intolerance, however, is a general term, describing an abnormal physiologic response to an ingested food or food additive. Diagnosis of food allergy aims to establish a reliable link between the clinical history of an adverse reaction to food as reported by the patient and the immunological basis of this reaction. In food allergy, an accurate diagnosis is extremely important, in particular to prevent patients from unnecessary and even potentially health threatening diets.Measurement of food-specific IgE antibodies by in vitro assays or skin testing are the routine procedures to diagnose food allergy. These diagnostic tests, however, indicate the presence of food-specific IgE antibodies, but they do not establish the diagnosis of food allergy. The final proof of the clinical relevance of the reported

SUMMARY The staining properties of tissue mast cells are influenced by the method of fixation. Differences in fixation and staining techniques may explain the contradictory results in the published reports on the number of human mucosal mast cells (MMC) in the gastrointestinal mucosa in health and disease.We have examined the influence of fixatives on the staining properties of human MMC in operative biopsy specimens of human jejunum. Specimens were divided into pieces, each of which was fixed in one of the following fixatives: Carnoy's, basic lead acetate (BLA), Baker's, Bouin's, isotonic formol-acetic-acid (IFAA), 10% neutral buffered formalin, formol sublimate, and formol saline.Thereafter, tissues were paraffin-embedded and 5 [km sections were cut and stained with either astra-blue/safranin pH 0-3, or Material and methodsOperative biopsies of normal jejunum were obtained from 13 patients who were undergoing abdominal surgery. In all cases the intestine was incised for resection or for creation of an anastomosis. Diagnoses were pyloric stenosis 4; adenocarcinoma of stomach or colon 3; duodenal ulcer 3; gastric ulcer 1; adhesions 1; unexplained abdominal pain 1. Each specimen was rinsed in cold saline and divided into eight pieces which were placed in fixative within 10 min. The period of fixation varied from one to seven days (except for Carnoy's) as indicated below. After fixation the tissues were embedded in paraffin; non-serial sections, 5 ,um thick, were cut and stained with astra-blue/safranin and with toluidine blue. Toluidine blue pH 0-54 Toluidine blue powder (0 5 g) (Gurr Chemical, Code Number 29880) was dissolved in 100 ml 0-5 N HCI (pH 0-5). The sections were taken to water as above and were stained with this solution for 30 min. They were rinsed in water for 5-10 min, differentiated in 95 % alcohol, and were cleared and mounted as above. METHOD FOR MAST CELL COUNTSMast cells were counted in well orientated sections cut perpendicular to the mucosa and in which the muscularis mucosae was intact. Counts were per- formed on coded slides on a Leitz Dialux 20 EB microscope (eyepiece x 10, objective x 40). A 10 mm2 eyepiece graticule, calibrated against a calibration slide was used. The edge of the graticule was orientated along the muscularis mucosae, at the base of the crypts. The area covered by the square of the graticule comprised 80-100 % of the total depth of the mucosa (from the bottom of the crypt to the tip of the villus) (Fig. 1). On each slide, eight to ten fields (290 ,um x 290 /tm; area 0 084 mm2) were counted and the MMC count per specimen was expressed as MMC/mm2. No attempt was made to correct for the area covered by epithelium. STATISTICAL ANALYSISResults are expressed as mean (x) and standard deviation (SD) or standard error of the mean (SE) and were compared by Student's t test. The reproducibility of duplicate counts on the same slide was assessed by linear regression analysis. ResultsOf the specimens obtained from the patients, 208 pieces of tissue were available for study, an...