Potential links between the emerging risk factors for food allergy and vitamin D status

A variety of hypotheses have been proposed to explain the recently described increase in food allergy among children living in developed countries. In this study, we summarize the emerging risk factors for IgE-mediated food allergy in early life, and then review the evidence for and against an association between low vitamin status (VDS) and food allergy. We consider whether each of the epidemiological variables that have been associated with food allergy may also be associated with VDS; and argue that future studies must adequately account for the potential relationships between risk factors for food allergy and VDS, and must also discriminate between vitamin D derived by sun exposure, diet and oral supplementation.

The role of self-injury in the organisation of behaviour

BACKGROUND

Self-injuring acts are among the most dramatic behaviours exhibited by human beings. There is no known single cause and there is no universally agreed upon treatment. Sophisticated sequential and temporal analysis of behaviour has provided alternative descriptions of self-injury that provide new insights into its initiation and maintenance.

METHOD

Forty hours of observations for each of 32 participants were collected in a contiguous 2-week period. Twenty categories of behavioural and environmental events were recorded electronically that captured the precise time each observation occurred. Temporal behavioural/environmental patterns associated with self-injurious events were revealed with a method (t-patterns; THEME) for detecting non-linear, real-time patterns.

RESULTS

Results indicated that acts of self-injury contributed both to more patterns and to more complex patterns. Moreover, self-injury left its imprint on the organisation of behaviour even when counts of self-injury were expelled from the continuous record.

CONCLUSIONS

Behaviour of participants was organised in a more diverse array of patterns when self-injurious behaviour was present. Self-injuring acts may function as singular points, increasing coherence within self-organising patterns of behaviour.

Maternal antenatal peanut consumption and peanut and rye sensitization in the offspring at adolescence

BACKGROUND

There is considerable controversy whether maternal peanut ingestion during pregnancy might influence sensitization in later life. Objective To examine whether maternal peanut ingestion during pregnancy might increase sensitization in the offspring.

METHODS

A population-based longitudinal cohort study with 16 years follow-up was conducted (N=373). Subjects were recruited at birth as part of an infant health study. Maternal antenatal peanut consumption was documented at birth and peanut and rye sensitization were determined by measurement of serum-specific IgE at age 16.

RESULTS

Peanut sensitization was common (14%). In the entire cohort (n=310), there was no association between antenatal peanut ingestion and peanut sensitization (P=0.17). However, there was a strong association between antenatal peanut ingestion and decreased risk of rye sensitization and peanut sensitization in those (n=201) without a family history (FH) of asthma (Rye OR 0.30, 95% CI 0.14-0.63, P=0.001 and Peanut OR 0.18, 95% CI 0.04-0.78, P=0.02). There was an increased risk of rye sensitization in those (n=108) with a FH of asthma and antenatal peanut ingestion (Rye OR 2.69, 95% CI 1.11-6.51 P=0.03). It was considered that these sensitizations were likely to be related to the presence of IgE antibodies to cross-reacting carbohydrate epitopes common to rye and peanut allergens.

CONCLUSIONS AND CLINICAL RELEVANCE

Antenatal peanut ingestion may influence the development of IgE antibody to cross-reacting carbohydrate epitopes in later life. Genetic factors may modify this association.

Food allergy: is strict avoidance the only answer?

It is an immunological paradigm that avoidance of food allergen may reduce the risk or prevent immunological reactions and conversely that a greater exposure increases the magnitude of the immune response. Consequently, food allergen avoidance has been recommended to reduce the risk of sensitization in infants and to prevent clinical reactions in children with positive skin prick tests (SPT). In the latter setting, it is hoped that avoidance may either promote or at least not retard the development of tolerance. Animal studies, however, have demonstrated that tolerance to food allergens may be induced by either large (high zone tolerance) or small (low zone tolerance) doses, whereas doses in between may actually stimulate immune responses. In this review, we discuss whether strict allergen avoidance is always the most appropriate strategy for preventing or managing IgE-mediated food allergy.

Rice: a common and severe cause of food protein-induced enterocolitis syndrome

OBJECTIVE

To examine and compare the characteristics of food protein-induced enterocolitis syndrome (FPIES) caused by rice and cow's milk/soy.

DESIGN

Retrospective study of children presenting with FPIES to the Children's Hospital at Westmead, NSW, Australia, over a 16-year period.

RESULTS

There were 14 children with 26 episodes of rice FPIES compared with 17 children with 30 episodes of cow's milk (n = 10) or soy (n = 7) FPIES. Children with rice FPIES were more likely to have FPIES caused by other foods (36%) than children with FPIES caused by cow's milk/soy (0%). Rice caused more episodes of FPIES before a correct diagnosis was made (median 4 (range 1-4) vs median 2 (range 1-4)) and triggered more severe reactions with higher rates of intravenous fluid resuscitation (42% vs 17%) than reactions caused by cow's milk/soy.

CONCLUSIONS

This study highlights the emerging importance of rice, a food commonly thought to be "hypoallergenic", as a significant trigger of FPIES. Paediatricians should be aware that rice not only has the potential to cause FPIES, but that such reactions tend be more severe than those caused by cow's milk/soy.

Adherence to allergy prevention recommendations in children with a family history of asthma

Allergen avoidance has been a major component of most programs for primary prevention of asthma and allergic diseases in childhood. As a part of the Childhood Asthma Prevention Study, families were provided with written and oral information on measures considered to be helpful in the primary prevention of allergic disease in high-risk infants. Dietary measures included advice to breastfeed for 6 months or longer, to delay the introduction of solid foods until after the infant turned 6 months of age, and to delay giving allergenic foods (egg and peanut butter) until after 12 months of age. In the active group of the randomized controlled trial aimed at reducing house dust mite (HDM) allergen levels, parents were advised to use an HDM-impermeable study mattress cover and an acaricide, to avoid sheep skins, and not to use a pillow before 12 months of age. Families received regular visits from the research nurses at 1, 3, 6, 9 and 12 months and phone calls every 6 wk. Only 43.4% of mothers were breastfeeding by 6 months and less than 20% by 12 months. The introduction of solid foods before 6 months was common, 26% by 3 months and 96% by 6 months. Adherence to infant-feeding recommendations was significantly greater in women over 30 yr of age, women who did not smoke during pregnancy, and women who had a tertiary education. Adherence to HDM reduction measures was greater than to those for infant feeding. The presence of symptoms in the form of an itchy rash by 4 wk did not significantly increase adherence. Complete adherence to infant-feeding recommendations in this intervention study of high-risk infants was low despite the provision of written information and reinforcement at home visits. In considering allergy prevention advice offered during clinical care, the likelihood of adherence is a factor which needs to be evaluated in assessing any potential benefits of allergy prevention regimens.

Early predictors for developing allergic disease and asthma: examining separate steps in the 'allergic march'

BACKGROUND

Sensitization and symptoms of allergic disease are strongly correlated, but little is known about the early clinical precursors of the development of allergen sensitization in childhood. The aim of this study was to identify these predictors, and to examine separately the effect of early sensitization on subsequent wheeze, asthma, rhinitis and eczema.

METHODS

In the Childhood Asthma Prevention Study, children with a family history of asthma were assessed for allergen sensitization, total serum IgE, wheeze, asthma, eczema and rhinitis at ages 18 months and 5 years. To examine predictors, at 18 months, for subsequent sensitization, children who were non-sensitized at 18 months and had data on sensitization at 5 years were investigated, n=375. To examine the predictors, at age 18 months, of subsequent onset of symptoms, children who did not have wheeze, asthma, eczema or rhinitis at 18 months were followed-up at 5 years, n=177.

RESULTS

Among children who were non-sensitized at age 18 months, the presence of eczema [adjusted relative risk (aRR), 1.67, 95% confidence interval (CI) 1.20-2.33], but not wheeze, asthma or rhinitis, was an independent predictor of the onset of sensitization by age 5 years. Among children who were asymptomatic at age 18 months, sensitization to any allergen at 18 months was an independent predictor for the presence of wheeze (aRR 2.41, 95% CI 1.28-4.55), asthma (aRR 4.66, 95% CI 1.88-11.54) and rhinitis (aRR 1.77, 95% CI 1.08-2.90), but not for the development of eczema (aRR 0.78, 95% CI 0.23-2.64) at 5 years.

CONCLUSION

In non-sensitized children, eczema, but not wheeze, asthma or rhinitis is a predictor for subsequent development of sensitization. This suggests that early childhood eczema, rather than wheeze and rhinitis, may promote subsequent allergen sensitization and raises the possibility that early management of eczema may reduce the prevalence of sensitization in children.

The association between infant feeding practices and subsequent atopy among children with a family history of asthma

BACKGROUND

Although longer duration of breastfeeding and later introduction of solid foods are both recommended for the prevention of asthma and allergic disease, evidence to support these recommendations is controversial.

OBJECTIVE

To examine the relation between infant feeding practices and the risk of asthma and allergic disease at age 5 years.

METHODS

A cohort of children with a family history of asthma in Sydney, Australia, was followed from birth to age 5 years. Data on infant feeding practices and on early manifestations of eczema were collected prospectively. The presence of eczema, asthma and atopy (positive allergen skin prick tests) were determined at age 5 years.

RESULTS

In 516 children evaluated at age 5 years, there was no significant association between the duration of breastfeeding or timing of introduction of solid foods and protection against asthma or other allergic disease, after adjustment for confounding factors. However, breastfeeding for 6 months or more and introduction of solid foods after 3 months were both associated with an increased risk of atopy at age 5 years (P=0.02 and 0.01, respectively). There was no significant association between the presence of eczema at 4 weeks and at 3 months and continued breastfeeding beyond those times.

CONCLUSION

Longer duration of breastfeeding and later introduction of solid foods did not prevent the onset of asthma, eczema or atopy by age 5 years.

Do immune responses to inhaled skin flakes modulate the expression of allergic disease?

We examine the nature of the immune responses to inhaled skin particles and query whether early exposure could play a role in providing protection against the development of allergic disease. Currently, the main hypothesis used to explain environmental modulation of allergic diseases, the 'hygiene hypothesis', is linked exclusively to microbial exposures acting upon the innate immune system. However, many of the exposures sustaining this hypothesis also involve co-exposure to skin flakes from humans or animals. Such skin flakes contain a complex mixture of antigens, glycolipids and small peptides that may induce immune responses. Should these responses prove relevant to the modulation of allergic diseases, it provides new opportunities to better understand the epidemic of allergic disease and to develop new interventions for its prevention.

EpiPen epidemic: suggestions for rational prescribing in childhood food allergy

There has been a marked increase in community concerns of the risk of food induced anaphylaxis in children and a consequent increase in the provision of the self or carer injectable epinephrine (EpiPen) (CSL Ltd, Parkville, Victoria, Australia)). The Australian use of EpiPens in children under 10 years has increased by 300% over 5 years with a crude rate of EpiPen provision of 1 per 544 Australian children aged under 10 years. However, the risk of a fatal reaction to food, particularly in preschool children, is remote (in Australia, an estimated one fatality in 30 years in the under 5-year-old population and two deaths in 10 years in the entire child population). It is therefore important to provide a perspective on the risk of death from food induced anaphylactic to parents and carers in view of the anxiety generated on this issue. The indications for provision of an EpiPen to children are not well defined. Six risk factors, which can be considered in evaluating the risk of a life-threatening reaction (age over 5 years; a history of respiratory tract involvement with the initial or subsequent reactions; a history of asthma requiring preventer medication; peanut or tree nut sensitivity; reactions induced by traces or small amounts of allergen; a strongly positive skin prick test) are proposed. It is suggested that the greater the number that are positive, the lower the threshold for provision of an EpiPen. In addition, instruction in EpiPen administration and the provision of both a clear and simple anaphylaxis action plan and a rational perspective on the remote risk of death is just as important as the provision of the device itself.

Age-related T cell responses to allergens in childhood

BACKGROUND

T cell priming, as determined by allergen-induced proliferative responses, is believed to occur principally in early childhood in both atopic and non-atopic infants under the influence of multiple factors including environmental allergen exposure. It is considered that T cell priming with expansion of Th2 cells is a crucial factor in the development of atopic disease.

OBJECTIVE

To examine T cell priming to commonly encountered allergens in childhood in relation to age.

METHODS

In a cross-sectional study T cell proliferation in relation to age was examined for three common allergens, ovalbumin (OVA), house dust mite (HDM) and rye grass pollen (RYE), in atopic and non-atopic children. The effect of age on Th1 (IFN-gamma) and Th2 (IL-5 and IL-13) cytokine production in response to these allergens was investigated to examine the possibility of immune deviation with time.

RESULTS

A significant increase in T cell proliferation with age was observed with RYE among atopic children only. However, the same was not observed with the two other allergens studied (i.e. OVA and HDM). In addition, RYE-induced (but not HDM or OVA) cytokine production showed an increased Th2 deviation with age as reflected in the increasing IL-5/IFN-gamma and IL-13/IFN-gamma ratios only among the atopic subjects with rye grass pollen sensitivity.

CONCLUSION

These findings suggest that grass pollen sensitivity in childhood is accompanied by a progressive accumulation of allergen-primed T cells and progressive deviation of the allergen-induced cytokine response towards a Th2 response in atopic subjects throughout childhood.

Polyclonal and allergen-induced cytokine responses in children with elevated immunoglobulin E but no atopic disease

BACKGROUND

Reduced Th1 and elevated Th2 cytokine responses are considered to be a principal mechanism in the generation of the inflammation leading to the manifestations of atopic disease in the skin of atopic dermatitis and in the airways of asthma. If reduced Th1 and elevated Th2 responses are principal determinants of the manifestation of atopic disease it might be expected that subjects with established disease would exhibit differences in their cytokine profiles as compared with atopic patients without clinical disease.

OBJECTIVE

To determine whether asymptomatic atopic children exhibit a cytokine imbalance similar to that seen in patients with established atopic disease or if they behave like non-atopic controls. Cytokine responses in a group of children with elevated IgE but no clinical manifestations of disease, atopic children with established disease and non-atopic controls were compared.

METHODS

We examined allergen-induced (house dust mite, HDM, rye grass pollen and RYE) cytokine responses in parallel with polyclonal (staphylococcal enterotoxin B, SEB) cytokine responses in a group of children with elevated serum IgE levels without current or past evidence of atopic disease (median age 6.6 years) and compared these with a non-atopic control group (median age 6.5 years) and a group of children with atopic disease (median age 6.7 years).

RESULTS

Symptomatic atopic children had reduced SEB-induced IFN-gamma and increased SEB-induced IL-4 and IL-5 as compared with non-atopic controls. In contrast, SEB-induced IFN-gamma, IL-4 and IL-5 production in asymptomatic atopics was not significantly different from the non-atopic control subjects. Allergen-induced Th1 (IFN-gamma) and Th2 (IL-5 and IL-13) cytokine production was increased in both symptomatic atopics and asymptomatic atopics when compared with non-atopic controls.

CONCLUSION

The defect in polyclonally induced IFN-gamma production was associated with the clinical manifestation of atopic disease but not the atopic stateper se. This suggests that the global reduction in IFN-gamma is the key determinant of the development of overt atopic disease. In contrast, elevated allergen-induced Th2 cytokine responses in children related to the atopic state per se irrespective of the presence of clinical atopic disease.

Increased Th1 and Th2 allergen-induced cytokine responses in children with atopic disease

BACKGROUND

Polyclonal cytokine responses following stimulation of T cells with mitogens or superantigens provides information on cytokine production from a wide range of T cells. Alternatively allergen-induced T cell responses can provide information on cytokine production by allergen-reactive T cells. While there is evidence of increased Th2 and reduced Th1 cytokine production following T cell stimulation with non-specific mitogens and superantigens, the evidence that Th1 cytokine production to allergens is decreased in line with a postulated imbalance in Th1/Th2 responses is unclear, with studies finding decreased, no difference or increased IFN-gamma responses to allergens in atopic subjects.

OBJECTIVE

To examine childhood polyclonal and allergen-induced cytokine responses in parallel to evaluate cytokine imbalances in childhood atopic disease.

METHODS

PBMC cytokine responses were examined in response to a polyclonal stimulus, staphylococcal superantigen (SEB), in parallel with two inhalant allergens, house dust mite (HDM) and rye grass pollen (RYE), and an ingested allergen, ovalbumin (OVA), in (a) 35 healthy children (non-atopic) and (b) 36 children with atopic disease (asthma, eczema and/or rhinitis) (atopic).

RESULTS

Atopic children had significantly reduced IFN-gamma and increased IL-4 and IL-5 but not IL13 production to SEB superantigen stimulation when compared with non-atopic children. HDM and RYE allergens stimulated significantly increased IFN-gamma, IL-5 and IL-13, while OVA stimulated significantly increased IFN-gamma production in atopic children.

CONCLUSION

We show that a polyclonal stimulus induces a reduced Th1 (IFN-gamma) and increased Th2 (IL-4 and IL-5) cytokine pattern. In contrast, the allergen-induced cytokine responses in atopic children were associated with both increased Th1 (INF-gamma) and Th2 (IL-5 and IL-13) cytokine production. The increased Th1 response to allergen is likely to reflect prior sensitization and indicates that increases in both Th1 and Th2 cytokine production to allergens exists concomitantly with a decreased Th1 response to a polyclonal stimulus in atopic children.

Ontogeny of T-helper 1 and T-helper 2 cytokine production in childhood

Compared to adults, infants and young children demonstrate differences in their immune response, indicating that there is maturation or change over time and it is probable that this may be reflected in cytokine production. Cytokine responses have been demonstrated to be different in atopic and non-atopic individuals. In this study, we examined T-helper 1 (Th1) (interferon-gamma [IFN-gamma]) and T-helper 2 (Th2) (interleukin [IL]-4, IL-5, and IL-13) cytokine release from atopic and non-atopic children in response to the staphylococcal superantigen, staphylococcal enterotoxin B (SEB). In non-atopic and atopic children, IFN-gamma, IL-4, and IL-5 release was significantly related to age. Non-atopic children younger than 2 years of age were found to have significantly reduced Th2 (IL-4, IL-5, and IL-13) responses when compared with older, non-atopic children. Atopic children had a reduced IFN-gamma response when compared with non-atopics in early childhood; however, the decreased IFN-gamma response seen in early childhood did not persist after 10 years. These age-related changes in cytokine production provide further support for the concept that cytokine deviations may determine the natural history of atopic disease during early childhood. In addition, the present study indicates the necessity of age-matched controls when examining children for both Th1 (IFN-gamma) and Th2 (IL-4) cytokine release.

Clinical correlates of response to pneumococcal immunization

OBJECTIVE

The inability to form antibodies to polysaccharide antigens may occur as a part of a more significant immunodeficiency or as an isolated defect. The latter has been reported in some children with recurrent upper and lower respiratory tract infections and evaluation of the responsiveness of such patients to polysaccharide antigens is indicated as part of their assessment. The present study evaluated the pattern of antibody responses of patients immunized with pneumococcal vaccine as part of the investigation of recurrent upper and lower respiratory tract infections to determine if any correlation exists between these responses and clinical presentation.

METHODOLOGY

An analysis was performed of antibody responses to pneumococcal serotypes 3, 4 and 6 following immunization with a 23-valent vaccine in 42 children with normal IgG levels who were evaluated for recurrent infections. Antibody responses were assessed in relation to clinical features and the results of other immunological investigations.

RESULTS

Of the 42 patients evaluated, 25 (59%) were responders to all serotypes tested. Failure to respond to serotype 3 alone was the least common pattern of non-response. Recurrent pneumonia, but not otitis media with discharge or chronic productive cough, was significantly associated with a lack of response to two or three serotypes. Failure to respond to serotype 3 alone or in combination with other serotypes was associated with more significant immune abnormalities.

CONCLUSION

In a selected population of children with recurrent bacterial infections, pneumococcal serotype 3 is a strong immunogen. In this clinical group recurrent pneumonia is associated with a defect in response to multiple pneumococcal serotypes.

Immune response to infection with Mycobacterium ulcerans

Mycobacterium ulcerans is a slow-growing, acid-fast bacillus that causes chronic necrotizing skin ulcers known as Buruli ulcers. Previously reported information on immunity to this mycobacterium is limited. We examined immune responses to M. ulcerans and M. bovis BCG in patients with M. ulcerans disease and in 20 healthy control subjects (10 tuberculin test positive and 10 tuberculin test negative). Cell-mediated immunity was assessed by stimulating peripheral blood mononuclear cells (PBMC) with whole mycobacteria and then measuring PBMC proliferation and the production of gamma interferon (IFN-gamma). Humoral immunity was assessed by immunoblotting. PBMC from all subjects showed significantly greater proliferation and IFN-gamma production in response to stimulation with living mycobacteria compared with killed cells. However, PBMC from subjects with past or current M. ulcerans disease showed significantly reduced proliferation and production of IFN-gamma in response to stimulation with live M. ulcerans or M. bovis than PBMC from healthy, tuberculin test-positive subjects (P < 0.001) and showed results in these assays comparable to those of tuberculin test-negative subjects (P > 0.2). Serum from 9 of 11 patients with M. ulcerans disease, but no control subject, contained antibodies to M. ulcerans. The results indicate that patients with M. ulcerans infection mount an immune response to M. ulcerans as evidenced by antibody production, but they demonstrate profound systemic T-cell anergy to mycobacterial antigens. These findings may explain some of the distinct clinical and pathological features of M. ulcerans-induced disease.

Cutaneous lymphocyte-associated antigen expression in children with atopic dermatitis and non-atopic healthy children

Cutaneous lymphocyte-associated antigen (CLA) is a cell surface glycoprotein which has been implicated in the homing of lymphocytes to cutaneous sites. It is postulated to play an important role in T-cell migration to skin in atopic dermatitis; however, the expression of CLA in both normal children and children with atopic dermatitis has not been extensively studied. If CLA expression on T cells were important in the traffic of lymphocytes to atopic dermatitis skin lesions, it might be expected that the proportion of CLA+ T cells in unstimulated peripheral blood from children with atopic dermatitis would be elevated. We have examined the proportion of CLA+ T cells in children with atopic dermatitis and non-atopic age-matched controls. The proportion of CLA+ T cells in non-atopic children was highly associated with and increased with increasing age (r = 0.88, p < 0.001). There was no difference between the proportion of T cells expressing CLA in the unstimulated peripheral blood mononuclear cells from children with severe (p = 0.18) or with mild/moderate (p = 0.3) atopic dermatitis and age-matched non-atopic controls. Despite this, children with atopic dermatitis did show evidence of perturbation of CLA expression, as unlike the non-atopic children the proportion of CLA+ T cells in the atopic children did not correlate with age. These findings suggest that while CLA expression may play a role in atopic dermatitis, other as yet undefined surface markers are likely to principally determine the migration of T cells to skin in atopic dermatitis.

Atopic eczema: its social and financial costs

Atopic dermatitis is a disorder with considerable social and financial costs. A recent Australian study indicates that the family stress related to the care of a child with moderate or severe atopic dermatitis is significantly greater than that of care of children with insulin-dependent diabetes mellitus. The factors contributing to family stress include: sleep deprivation; loss of employment; time taken for care of atopic dermatitis; and financial costs. An estimate of the yearly financial costs for a family and community (which includes medical, hospital, direct costs of treatments and indirect costs from loss of employment), range from $A1142 per child per year with mild atopic dermatitis, to $A6099 per year for a child with severe atopic dermatitis. As the current prevalence of atopic dermatitis in Australia is 10-15%, this indicates a considerable financial burden on the community. It is possible that appropriate interventions directed to reducing trigger factors, may produce worthwhile savings, in addition to benefits for the individuals and families. Atopic dermatitis should not be regarded as a minor skin disorder but as a condition which has the potential to be a major handicap involving considerable personal, social and financial consequences both for the family and for the community.

Pooled human immunoglobulin inhibits IL-4 but not IFN-gamma or TNF-alpha secretion following in vitro stimulation of mononuclear cells with Staphylococcal superantigen

Intravenous immunoglobulin preparations have been successfully used in many disorders, where immunomodulation rather than immunoglobulin replacement has been the goal of therapy. The exact mechanisms by which immunoglobulin exerts its immunomodulatory effects are unclear. Proposed mechanisms include modification of T cell activation and alteration to cytokine production. As intravenous immunoglobulin therapy has been used in a number of disorders where superantigens are proposed to play a role in the disease pathogenesis, we have examined the effect of in vitro human pooled immunoglobulin on cytokine production from peripheral blood mononuclear cells in response to activation with the Staphylococcal superantigen Staphylococcal enterotoxin B. The authors found inhibition of secretion of interleukin 4 (IL-4) (P<0.001) but not interferon gamma (IFN-gamma) (P=0.13) or tumour necrosis factor alpha (TNF-alpha) (P=0.66) by pooled immunoglobulin at concentrations (6 g/l) which approximate the rise in serum immunoglobulin following in vivo IVIG therapy. Mononuclear cell proliferation was also inhibited by addition of pooled immunoglobulin to superantigen stimulated cultures. These effects do not relate to specific anti-staphylococcal enterotoxin B antibodies in the immunoglobulin preparation. The authors show that pooled human immunoglobulin can differentially modulate the secretion of IL-4 and IFN-gamma in response to superantigen stimulation.

Intracellular interferon-gamma (IFN-gamma) production in normal children and children with atopic dermatitis

A reduction in the in vitro production of IFN-gamma has been consistently described in atopic dermatitis (AD). Whether this reduction is due to a decrease in the population of peripheral blood mononuclear cells (PBMC) producing IFN-gamma or reduced IFN-gamma production per cell, or a combination of both is not clear. We have examined the intracellular production of IFN-gamma in children with AD and in healthy non-atopic controls. As Staphylococcus aureus colonization is a feature of childhood AD, and is postulated to contribute to the cutaneous inflammation in atopic dermatitis, S. aureus and Staphylococcal enterotoxin B (SEB) were used to activate PBMC. Stimulated PBMC from subjects with AD had significantly fewer IFN-gamma-containing cells in response to SEB (P < 0.001) and S. aureus (P < 0.01) than normal non-atopic children. In addition, SEB-stimulated PBMC from children with AD had less IFN-gamma per cell than normal non-atopic children (P < 0.01). Reduction in the proportion of cells containing IFN-gamma was seen in CD4+, CD8+ and natural killer (NK) cells in PBMC from children with AD. Our findings indicate that reduced production of IFN-gamma observed in childhood AD is due to both a decrease in the number of IFN-gamma-producing cells and a reduced amount of IFN-gamma production per cell. Furthermore, we found that this defect was not confined to CD4+ T cells, suggesting a more generalized defect in IFN-gamma production in childhood AD.

Production of antibodies to staphylococcal superantigens in atopic dermatitis

Staphylococcal superantigens (SAG) are implicated in the inflammation of atopic dermatitis. As SAG mediated diseases may be modified by specific antibodies, the antibody response to SAG in atopic dermatitis was investigated. Immunoglobulin (Ig) G to staphylococcal enterotoxin A (SEA), staphylococcal enterotoxin B (SEB), and toxic shock syndrome toxin 1 (TSST-1) were measured by sandwich enzyme linked immunosorbent assay (ELISA) in 74 children with atopic dermatitis and 111 controls. Controls had detectable IgG to SEA, SEB, and TSST-1, which increased with age. Atopic dermatitis subjects had an increased response to SEB at 6 months to 2 years (76% v 42%) and 2 to 7 years (79% v 57%), and equivalent responses to SEA and TSST-1, compared to controls. It is suggested that increased responses to SEB relate to increased colonisation and hence exposure to superantigen producing staphylococcus in atopic dermatitis, and that inflammation of atopic dermatitis is not caused by an inability to make antibody to SAG.

Enhanced IL-4 but normal interferon-gamma production in children with isolated IgE mediated food hypersensitivity

Atopic disorders such as atopic dermatitis and asthma have been characterised by an imbalance in interferon-gamma (INF-gamma) and IL-4. Whether similar imbalances are found in atopic disorders with different clinical manifestations, such as IgE mediated immediate food hypersensitivity, is not clear. We have examined the in vitro production of INF-gamma and IL-4 in peripheral blood mononuclear cells (PBMC) following phytohaemagglutinin stimulation from children with isolated immediate IgE mediated food hypersensitivity (egg, milk, "nut"), children with moderate and severe atopic dermatitis, and normal children. Children with immediate food reactions were excluded if they had a history or evidence of atopic dermatitis or asthma. PBMC from children with IgE mediated food hypersensitivity produced significantly more IL-4 (p = 0.013) but equivalent INF-gamma (p = 0.26) compared to PBMC from control children. In contrast, PBMC from children with atopic dermatitis produced significantly less INF-gamma (p < 0.001) and more IL-4 (p < 0.008) than PBMC from normal children. In addition, there was no difference in IL-4 (p = 0.74) but significantly less INF-gamma (p < 0.001) produced by PBMC from the children with atopic dermatitis than food hypersensitivity. We demonstrate that children with IgE mediated food hypersensitivity and no other manifestation of atopic disease have enhanced IL-4 production without the defect in INF-gamma production observed in childhood AD and asthma. We postulate that isolated IL-4 enhancement promotes the development of IgE mediated hypersensitivity disorders such as food allergy, whilst the combination of defective INF-gamma and enhanced IL-4 production promotes inflammatory atopic disorders such as AD and asthma.

The Melbourne House Dust Mite Study: long-term efficacy of house dust mite reduction strategies

BACKGROUND

Asthma severity among mite-sensitized individuals appears to be related to the degree of mite allergen exposure.

OBJECTIVES

The objective of this study was to assess the long-term effectiveness of mite avoidance measures in the homes of asthmatic children in Melbourne, Australia.

METHODS

The concentration of house dust mite allergen (Der p 1) was measured on the child's mattress surfaces and bedroom floors in 85 homes on 10 occasions over a 16-month period. After the first three visits, all mattresses were covered with a semipermeable encasement, and carpeted bedroom floors were randomly allocated to regular applications of a placebo or an "anti-mite" shampoo.

RESULTS

The concentration of Der p 1 recovered was initially high in the carpeted bedrooms (n = 66) (41.1, 95% confidence interval, 30.7 to 55.0 microg Der p 1 per gm) and mattresses (n = 85) (39.6, 27.2 to 57.7). During the initial observation period the concentration of mite allergen fell in the treatment, placebo, and parental control groups. During the seven treatment periods, no differences were seen between the Der p 1 concentrations in the groups using the "anti-mite" shampoo, placebo shampoo, or the parental control group (e.g., at visit 4; 12.6, 8.2 to 19.5; 14.8, 8.6 to 25.1; and 12.0, 8.1 to 17.7 microg/gm, respectively). In contrast, the concentration of Der p 1 in samples from uncarpeted floors and mattress encasements was low (4.1, 2.1 to 8.0 microg/gm and 4.2, 2.6 to 6.5 microg/gm, respectively) and insufficient dust for analysis was frequently obtained from these sites.

CONCLUSIONS

There was no additional benefit from the use of an "anti-mite" shampoo. The absence of carpets and the use of mattress encasements was a useful long-term strategy for mite allergen avoidance.

Pulmonary diseases in children with severe combined immune deficiency and DiGeorge syndrome

Pulmonary disease is a common presenting feature and complication of T-cell immunodeficiency. We retrospectively reviewed 15 children with severe combined immune deficiency (SCID) and 19 children with DiGeorge syndrome at the time of their first presentation to the Royal Children's Hospital in the 15-year period from 1981 to 1995. In children with SCID, pulmonary disease was a common (67%) presenting feature and the organisms identified were Pneumocystis carinii (PCP) (n = 7), bacteria (n = 4), viruses (n = 3), and a fungus (n = 1). Late pulmonary complications included lower respiratory tract infections, bronchiolitis obliterans, and lymphointerstitial pneumonitis. Pulmonary infections were common (17 occasions) and the organisms identified were bacteria (n = 7), viruses (n = 6), fungi (n = 3), and Mycobacterium tuberculosis (n = 1). Pulmonary complications were responsible for 5 of 9 deaths. PCP was not identified as a late complication in any child, presumably as a result of effective prophylactic therapy. Although pulmonary disease was not a major presenting feature in children with DiGeorge syndrome, pulmonary complications were common. These included recurrent bacterial and viral infections and bronchomalacia, which complicated management and predisposed to morbidity and mortality, even in those without a T-cell defect. We conclude that pulmonary disease is a common manifestation in children with SCID and DiGeorge syndrome.

Fatal granulomatous amoebic encephalitis caused by Balamuthia mandrillaris

Granulomatous amoebic encephalitis caused by Balamuthia mandrillaris is rare (63 human) cases reported worldwide) and fatal. We report a case in a five-year-old boy who had previously been well. For 18 months, he had had a slowly progressive, granulomatous mid facial lesion, but despite extensive investigation definitive diagnosis was made only with the acute onset of neurological signs in the last two weeks of life, when a brain biopsy specimen revealed amoebic trophozoites and cysts. Infection with B. mandrillaris should be considered in the differential diagnosis of chronic skin lesions with non-specific granulomatous histopathology and negative microbiological test results.

The Melbourne house dust mite study: eliminating house dust mites in the domestic environment

BACKGROUND

Hypersensitivity to house dust mite allergens is associated with increased asthma morbidity. Asthma severity appears to be related to the degree of mite allergen exposure. Short-term studies suggest that complete avoidance reduces disease severity.

OBJECTIVE

The study was designed to assess the effect of different mattress covers and floor coverings on mite allergen concentrations in the homes of mite-sensitive children with asthma in the city of Melbourne, Australia.

METHODS

Mite allergen Der p 1 concentration was measured on mattress covers, mattress surfaces, and carpeted and uncarpeted floors in 107 dwellings; and measurement was performed on three occasions over a 5-month period. After the first sampling, all mattress covers and impermeable encasements were permanently removed.

RESULTS

The initial geometric mean concentrations of Der p 1 (micrograms per gram of fine dust) from the surfaces of sheepskin, wool, and cotton mattress coverings were greater than those from the surfaces of impermeable mattress encasements (116, 113, and 19 vs 0.4) (p < 0.001); corresponding concentrations on the underlying mattresses were 142, 38, 20, and 0.6, respectively (p < 0.05 to 0.001). At the end of the study these mattress surface concentrations were 79, 65, 9.7, and 3.1, respectively. In 24 dwellings an uncarpeted room was adjacent to a carpeted room. At each visit the concentration of Der p 1 in uncarpeted rooms was below the reported threshold for sensitization and significantly less than that in the adjacent carpeted room.

CONCLUSION

In homes of children with asthma, "asthmogenic" concentrations of Der p 1 were found on nonencased mattresses and carpeted floors, but the use of impermeable mattress encasements and carpet exclusion were associated with concentrations of Der p 1 below the reported threshold for sensitization.

Atopic eczema: its impact on the family and financial cost

OBJECTIVE

To evaluate the impact of childhood atopic eczema on families and assess the personal financial cost of its management.

DESIGN

Cross sectional survey.

SETTING

Paediatric dermatology and paediatric diabetology outpatient clinics.

PATIENTS

Parents of 48 randomly selected children with atopic eczema and 46 with insulin dependent diabetes mellitus.

MAIN OUTCOME MEASURES

The impact on family score, the reported cost of relevant medical treatments, medical consultations, relevant hospitalisation, and income loss.

RESULTS

Families of children with moderate or severe atopic eczema had a significantly higher impact on family score than families of diabetic children. A conservative estimate of the annual personal financial cost of managing mild, moderate, and severe eczema was Aus$330, 818, and 1255, respectively. The financial cost to the community for the management of atopic eczema in the study groups was greater. The personal financial cost of managing eczema was greater than for asthma.

CONCLUSION

Childhood atopic eczema has a profound impact on the social, personal, emotional, and financial perspectives of families.

Proliferation and production of interferon-gamma (IFN-gamma) and IL-4 in response to Staphylococcus aureus and staphylococcal superantigen in childhood atopic dermatitis

We have examined the cell-mediated immunity (CMI) to Staphylococcus aureus (S. aureus) and Staphylococcal enterotoxin B (SEB) in peripheral blood mononuclear cells (PBMC) from children with atopic dermatitis (AD) and from non-atopic child controls by measurement of proliferative responses and production of the cytokines IFN-gamma and IL-4. PBMC from children with AD showed significantly higher proliferative responses to both S. aureus (P < 0.01) and SEB (P < 0.05). Despite this enhanced proliferation, production of IFN-gamma in response to S. aureus (P < 0.001) and SEB (P < 0.01) from these PBMC was significantly diminished. In contrast, PBMC from children with AD were significantly more likely to produce IL-4 in response to S. aureus (P < 0.01). These findings demonstrate in vitro heightened CMI to S. aureus in children with AD, and implicate S. aureus as a potent inflammatory stimulant. Impaired IFN-gamma production to S. aureus in vivo may result in failure to eradicate S. aureus from skin. The organism's persistence on skin would contribute to inflammation by causing continued T cell activation and release of pro-inflammatory mediators.

New perspectives on inflammation in atopic dermatitis

Recent information implicates the stimulation of T cells by Staphylococcus aureus antigens and exotoxins as a likely factor in provoking the inflammatory response in atopic dermatitis. S. aureus secrets exotoxins called superantigens, which stimulate a large proportion of T cells. In addition, protein A, a component of the cell wall of S. aureus, is a potent B cell mitogen. This understanding provides a rationale for attempting to reduce the staphylococcal skin colonization of patients with severe atopic dermatitis and correlates with the clinical observation in a number of situations of marked improvement in atopic dermatitis following antibiotic treatment.

Interleukin-4 and interferon-gamma production in atopic and non-atopic children with asthma

Previous studies have demonstrated increased production of interleukin-4 (IL-4) and reduced production of interferon (IFN)-gamma in stimulated peripheral blood mononuclear cell cultures from children and adults with atopic dermatitis, however, it is unclear whether such an imbalance of cytokine production relates to other childhood atopic diseases such as asthma, and in particular to the presence of the atopic state per se. The production of IL-4 and IFN gamma in phytohaemagglutin- (PHA)-stimulated peripheral blood mononuclear cell (PBMC) cultures from atopic and non-atopic children with moderately severe chronic persistent asthma, and a group of age-matched non-atopic controls who did not have asthma was examined. Atopic children with asthma produced significantly more IL-4 and less IFN gamma than non-atopic children with asthma and non-atopic controls who did not have asthma. There was no significant difference in IL-4 or IFN gamma production between non-atopic children with asthma and controls. These findings demonstrate that an imbalance of IL-4 and IFN gamma production is present in atopic asthma as previously documented in atopic dermatitis, therefore suggesting that it is a feature of the atopic state per se.

Ontogeny of IL4 production

There is evidence to suggest that the production of some cytokines in childhood is different to that in adults. The production of IL4 in PHA-stimulated PBMC cultures was examined in healthy neonates, children and adults to determine the ontogeny of IL4 production throughout childhood. In vitro IL4 production was found to be significantly reduced in neonates and children under 10 years of age as compared to adults, and to increase progressively with age. The mechanisms leading to reduced IL4 production in neonates were shown to be different to those in children, with a defect in signal transduction demonstrated for lymphocytes from neonates but not children < 10 years. The presence of an inhibitory factor in cord blood plasma was also noted. These age-dependent variations in IL4 production and response to stimulation with PMA/Ca may reflect differences in naive and memory T cell populations.

Cow milk allergy within the spectrum of atopic disorders

In order to examine the relationship between cow milk allergy (CMA) and atopic disorders in childhood, a consecutive group of 42 infants with IgE mediated CMA was followed for at least 2 years. The incidence of sensitization to common food and inhalant antigens and the development of eczema, asthma, and food allergies was examined for the cohort and compared between patients whose CMA remitted and those with persistent disease. In this cohort the prevalence of eczema was 57%, asthma 69%, egg allergy 67%, peanut allergy 55%, and 83% of infants demonstrated positive skin-prick tests to three or more allergens. At the end of the study CMA had remitted in 13 patients (median age 44 months) whereas in 29 patients it persisted (median age 44 months). Although there was no significant difference in the incidence of eczema or asthma during the study between these two patient groups, the incidence of allergy to egg and peanut butter was significantly greater for children with persistent CMA. Consistent with our hypothesis that children with persistent CMA have a more severe dysregulation of IgE synthesis than those whose disease remits, patients with persistent CMA had a significantly higher incidence of and level of skin sensitivity to inhalant and other dietary allergens. Sensitization to the inhalant allergens Dermatophagoides pteronyssinus, cat dander and rye grass was frequently seen in early infancy and increased during the study period. Thus, children with IgE mediated CMA frequently generate IgE responses to multiple dietary and inhalant allergens in infancy and early childhood and develop immediate hypersensitivity to other foods as well as clinical eczema, and asthma.

Reduced interferon-gamma secretion in neonates and subsequent atopy

Low interferon-gamma (IFN-gamma) secretion has been found in individuals with active atopic disease. Whether this is a cause or result of the disease process is uncertain. Cord blood IFN-gamma secretion was examined in 35 neonates who were then prospectively followed up for 1 year for the development of atopic disease. Infants who developed either symptoms of atopic disease or a positive IgE-mediated skin prick test at 12 months of age produced significantly less IFN-gamma at birth compared with those who did not (p = 0.005). This reduced secretion of IFN-gamma at birth indicates that the defect in interferon secretion is a primary component of the atopic state rather than an effect of the disease process.

Spontaneous expression of IL-4 mRNA in lymphocytes from children with atopic dermatitis

Normal lymphocytes do not generally produce or secrete lymphokines in the resting or unstimulated state and only express or release cytokines following activation. Recently, the spontaneous production of intracellular interferon-gamma (IFN-gamma) and spontaneous secretion of IL-6 has been documented in patients with atopic dermatitis. These findings indicated that lymphocytes had been previously activated in vivo. Such in vivo activation may also be associated with spontaneous production of IL-4. As measurement of IL-4 secretion by immunoassay is complicated by poor sensitivity, and only provides information on the net amount of cytokine present after secretion, adsorption, consumption and degradation have occurred, IL-4 mRNA expression in peripheral blood lymphocytes from children with atopic dermatitis and controls was examined by polymerase chain reaction (PCR)-assisted mRNA amplification. Spontaneous expression of IL-4 mRNA was detected in four of eight patients with severe atopic dermatitis. Following stimulation in vitro, seven of eight atopic patients demonstrated detectable IL-4 mRNA. In comparison, no spontaneous expression of IL-4 mRNA was found in controls, and only six of 10 controls expressed IL-4 mRNA in stimulated cultures. The spontaneous expression of IL-4 mRNA in unstimulated cultures from children with atopic dermatitis supports the possibility that previous in vivo activation has occurred, and suggests that IL-4 production is increased in vivo in atopic dermatitis. This in vivo activation together with the constitutive expression of IL-4 mRNA are likely to contribute to the spontaneous in vitro production of IgE in atopic patients.

Reduced interferon-gamma (IFN-gamma) secretion with increased IFN-gamma mRNA expression in atopic dermatitis: evidence for a post-transcriptional defect

Reduced secretion of IFN-gamma in atopic individuals has been implicated in the pathogenesis of disease, though the mechanisms leading to this reduced secretion have not been elucidated. As production of IFN-gamma has been shown to be predominantly regulated by its rate of transcription, expression of IFN-gamma mRNA was examined in atopic children and in age-matched, non-atopic controls by polymerase chain reaction (PCR)-assisted mRNA amplification. Children with atopic dermatitis were found to have constitutive expression of IFN-gamma mRNA in freshly isolated peripheral blood mononuclear cells (PBMC) and in unstimulated PBMC cultures which increased further following stimulation with phorbol myristate acetate (PMA)/Ca in vitro. In contrast, expression of IFN-gamma mRNA in controls was only detected in stimulated cultures, as has been demonstrated previously for normal adults. These findings demonstrate that circulating T cells from atopic children have been activated in vivo, and suggest that T cell activation is a significant component of the inflammatory process in atopic dermatitis. Although expression of IFN-gamma mRNA was increased in the atopic children, secretion was confirmed to be significantly lower than in controls, indicating that the defect(s) underlying reduced IFN-gamma secretion in these individuals lie post-transcriptionally.

Features of transient hypogammaglobulinaemia in infants screened for immunological abnormalities

The incidence of transient hypogammaglobulinaemia of infancy (THI) detected in a major paediatric centre over a 10 year period was examined. A total of 2468 subjects less than 2 years of age had an IgG measurement taken between July 1979 and March 1990. Subjects with known immunodeficiencies were excluded. Fifteen patients were classified as having THI with an initial IgG level less than the fifth centile followed by a second measurement within the normal range. A further 24 patients were identified as having possible THI with a single low IgG concentration. There were 60,174 live births each year in Victoria in the years 1979-88. This gives an incidence of proved THI of 23 per 10(6) births, and including proved and probable THI an incidence of 61 per 10(6) live births. Of those patients with proved THI 12/15 had symptoms of either atopic disease or food allergy/intolerance and three had gastrointestinal symptoms without any evidence of atopic disease. At presentation 12/15 (80%) were IgA deficient and 9/15 had IgM concentrations less than the 20th centile for age. It is suggested that in view of the preponderance of atopic and food intolerant patients that subclinical protein loss from the bowel due to allergic inflammation may be a contributing factor to the development of THI in some patients.

Food allergy in children

Food allergy is a common condition among infants. The reactions are usually to milk, egg and peanut products. They frequently improve with time. It is important for the practitioner to recognise the occurrence of these reactions and to advise parents of their significance.

Growth hormone deficiency and combined immunodeficiency

The first description of an association of isolated growth hormone deficiency (IGHD) and combined immunodeficiency is presented. The findings suggest that IGHD should be considered as a cause of short stature in children with combined immunodeficiency before attributing growth retardation to infection.

Delayed umbilical cord separation in alloimmune neutropenia

Delayed umbilical cord separation in association with neonatal alloimmune neutropenia is reported. Delayed umbilical cord separation has been described in association with defects in neutrophil function. The present case indicates that deficiency in neutrophil number should also be considered as a cause of delayed cord separation.