EAACI food allergy and anaphylaxis guidelines. Primary prevention of food allergy.

Food allergy can have significant effects on morbidity and quality of life and can be costly in terms of medical visits and treatments. There is therefore considerable interest in generating efficient approaches that may reduce the risk of developing food allergy. This guideline has been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Taskforce on Prevention and is part of the EAACI Guidelines for Food Allergy and Anaphylaxis. It aims to provide evidence-based recommendations for primary prevention of food allergy. A wide range of antenatal, perinatal, neonatal, and childhood strategies were identified and their effectiveness assessed and synthesized in a systematic review. Based on this evidence, families can be provided with evidence-based advice about preventing food allergy, particularly for infants at high risk for development of allergic disease. The advice for all mothers includes a normal diet without restrictions during pregnancy and lactation. For all infants, exclusive breastfeeding is recommended for at least first 4-6 months of life. If breastfeeding is insufficient or not possible, infants at high-risk can be recommended a hypoallergenic formula with a documented preventive effect for the first 4 months. There is no need to avoid introducing complementary foods beyond 4 months, and currently, the evidence does not justify recommendations about either withholding or encouraging exposure to potentially allergenic foods after 4 months once weaning has commenced, irrespective of atopic heredity. There is no evidence to support the use of prebiotics or probiotics for food allergy prevention.

Direct measurement of cytokines (IFN-gamma, IL-4, -5, and -6) from organs after antigenic challenge.

A mouse in vivo model has been developed in which cytokines produced within the regional lymph nodes and other organs after an antigenic challenge were measured directly without the need of an in vitro reculturing step. Mice were subcutaneously (s.c.) immunized with antigens such as keyhole limpet hemocyanin (KLH) in aluminium hydroxide (alum) at the base of the tail. After defined periods of time lymph nodes, spleen, liver, and lung were collected and frozen. The organs were then homogenized (or sonicated), centrifuged, and the cytokine levels, for example, IFN-gamma, IL-4, IL-5, and IL-6 were determined by ELISA. It was found that injection of alum alone caused measurable cytokine production in draining lymph nodes, but inoculation of an antigen-alum mixture, such as KLH and dust-mite antigen (DMA), significantly increased in vivo cytokine production over that of alum alone. In the dose range tested there appeared to be an inverse relationship between the dose of antigen and cytokine levels. Thus, 0.1-microgram KLH induced more IL-4 in vivo than 10-micrograms KLH. Kinetic studies showed that for IL-4 and IFN-gamma, peak production occurred around days 5 and 6, respectively. Route of immunization and the dose of antigen were found to be very critical, in that injection of 10-micrograms DMA intraperitoneally induced significant levels of cytokines in the lung, while the same dose of antigen given at the base of tail, s.c., did not induce appreciable levels of cytokines in any organ tested. Cyclosporin A inhibited in vivo production of IFN-gamma, IL-4, and IL-5 by approximately 80%, but not that of IL-6. Surprisingly, dexamethasone enhanced the production of IL-6 while inhibiting all the other cytokines. In conclusion, these results suggest that direct determination of cytokines in the organs may provide an easy readout to assess differential effects of immunoregulatory molecules on the production of Th1- and Th2-type cytokines in vivo.

Cytokine immunotrapping: an assay to study the kinetics of production and consumption or degradation of human interferon-gamma.

With the aim of determining the rate of cytokine production, we have investigated immunoassay conditions which prevent consumption/degradation. These assays, termed cytokine immunotrapping assays (CITA), are based on early capturing of cytokines secreted during cell culture by immobilised or soluble mAbs and a recently described chemiluminescent immunoassay. Here we describe assay conditions using IFN-gamma as a prototype cytokine. For production of IFN-gamma, PBMC, purified CD4+ or CD8+ T cells, or diluted whole blood were cultured with different T cell stimulating agents. Polystyrene macrobeads precoated with an anti-IFN-gamma mAb were put in culture and after a defined incubation period, a dimethyl acridinium ester (DMAE)-labelled second anti-IFN-gamma mAb and sodium azide were added into the culture for additional 24 h. The beads were washed and chemiluminescence signals determined in a luminometer. Trapping experiments were also performed with the beads or the soluble mAbs alone. Irrespective of the configuration, IFN-gamma concentrations measured in trapping conditions were always higher (3-20-fold) than in conventional cultures. By using the best trapping combination, i.e. both bead-mAb1 and DMAE-mAb2 added at the start of culture (single step), it was possible to detect IFN-gamma production as early as 2 h. Also, IFN-gamma secreted by less than 500 PBMC or whole blood cells could be detected within 24 h. When purified CD4+ or CD8+ cells were used instead of PBMC, a reduction of the trapping effect was observed. Conversely, addition of monocytes to purified T cells increased the trapping factor suggesting that a substantial amount of IFN-gamma was consumed or degraded both by CD14+ cells as well as T cells in culture. Preliminary results show that this assay is also suitable for the early detection of IL-1 and IL-4 which are known to be more tightly regulated. Thus, the new principle described here is expected to be useful in clinical settings where both the time and amounts of material are limited to investigate the role of cytokines in particular disease.

Cerebrospinal fluid interleukin-1 beta/interleukin-1 receptor antagonist balance and tumor necrosis factor-alpha concentrations in tuberculous, viral and acute bacterial meningitis.

The levels of interleukin-1 beta, IL-1 receptor antagonist and tumor necrosis factor-alpha (TNF-alpha) were analyzed in 19 cases of tuberculous, 14 cases of viral, and 22 cases of acute bacterial meningitis, and in 18 control subjects. 20 patients (91%) with acute bacterial and 8 (42%) with tuberculous meningitis had detectable amounts of TNF-alpha in the initial cerebrospinal fluid (CSF) sample (mean 1044 +/- 131 pg/ml, range 95-1950, and mean 61 +/- 23 pg/ml, range 25-300, respectively), whereas TNF-alpha was not detectable in any of the patients with viral meningitis, or in any of the control subjects. IL-1 beta levels were 767 +/- 110 pg/ml (185-2000) in acute bacterial, 345 +/- 63 pg/ml (50-670) in tuberculous, 257 +/- 70 pg/ml (20-700) in viral meningitis, and 37 +/- 4 pg/ml (10-68) in control subjects. Il-1 receptor antagonist concentrations were significantly elevated in all meningitis groups, without significant differences between the groups. Il-1 receptor antagonist levels were 2487 +/- 62 pg/ml (2250-2950) in acute bacterial, 2216 +/- 82 pg/ml (1350-2550) in tuberculous and 1985 +/- 92 pg/ml (650-2500) in viral meningitis, and 154 +/- 26 pg/ml (20-245) in control CSF samples. A positive correlation was found between TNF and IL-1 beta levels (p < 0.01), and TNF levels and conscious state (p < 0.05). The ratio of concentrations of IL-1 receptor antagonist to IL-1 beta was 3.2 in acute bacterial meningitis, 6.9 in tuberculous meningitis and 8.3 in viral meningitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunological evaluation of erythema nodosum in tularaemia.

During two tularaemia outbreaks in the Bursa region of Turkey in 1991, a total of 98 patients were diagnosed and evaluated. Thirteen of these patients had erythema nodosum, which is accepted as a secondary skin manifestation. The patients with erythema nodosum, 21 patients without any skin lesions, and 20 healthy controls were studied. Comparable elevations of levels of IgG, IgA, and IgM were detected in the two tularaemia groups. There was no difference in complement C3c and C4 levels between the groups. All of the patients with erythema nodosum had elevated circulating immune complex (CIC) levels, when compared with the patients without skin lesions and the control group. The acute phase response (C-reactive protein [CRP] and erythrocyte sedimentation rate [ESR]) of the erythema nodosum group was significantly higher than the patients with normal skin, and healthy controls (P < 0.001). Serum transferrin levels were significantly decreased in both of the tularaemia groups (P < 0.001). Serum soluble interleukin-2 receptor levels (SIL-2R) were significantly elevated in both tularaemia groups (P < 0.001), and the elevation was more marked in the erythema nodosum group (P < 0.05). Histopathological evaluation of biopsies from two patients with erythema nodosum showed dermal oedema, a perivascular lymphocytic infiltrate, and panniculitis. No immunoglobulin or complement deposits were detected on immunofluorescence. Erythema nodosum in the course of tularaemia is associated with many immunological changes, although it is not clear whether these findings are related to the increased tissue response, or whether they play a role in the pathogenesis of the erythema nodosum.