Allergens and endotoxin in settled dust from day-care centers and schools in Oslo, Norway

Allergy to indoor allergens can cause frequent and severe health problems in children. Because little is known about the content of allergens in the indoor environments in Norway, we wanted to assess the levels of cat, dog and mite allergens in schools and day-care centers in Oslo. Allergen levels in dust samples from 155 classrooms and 81 day-care units were measured using commercially available enzyme-linked immunosorbent assay (ELISA) kits. Additionally, we measured the levels of endotoxin in 31 day-care units, using the limulus amebocyte lysate test. Most of the dust samples contained detectable amounts of cat and dog allergens. In mattress and floor dust (day-care centers), and curtain and floor dust (schools) the median Fel d 1 levels were 0.17, 0.002, 0.02 and 0.079 microg/m2, while the median Can f 1 levels were 1.7, 0.03, 0.1 and 0.69 microg/m2, respectively. Levels of cat and dog allergens in school floor dust were associated with the number of pupils with animals at home. In contrast, <1% of the samples had measurable levels of the mite allergen Der p 1. Moreover, the levels of endotoxin tended to be higher in dust from floors (1.4 ng/m2) compared with that from mattresses (0.9 ng/m2).

PRACTICAL IMPLICATIONS

To reduce allergen exposure, allergic individuals should be placed in the classes/rooms with the fewest pet owners. Moreover, mattresses in day-care centers are major reservoirs of cat and dog allergens and should be cleaned frequently.

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.

Maternal allergen immunization during pregnancy in a mouse model reduces adult allergy-related antibody responses in the offspring

BACKGROUND

The immune status and allergen exposure of the mother may influence the immune response in the offspring after birth. This relationship may be important both for allergen avoidance strategies and, alternatively, for allergy prophylaxis by allergen exposure of the mother.

OBJECTIVE

The aim of the present study was to investigate the effect of allergen immunization of the mother during pregnancy and postpartum, in relation to the allergy-related immune response (IgE) and the non-allergy-related (IgG2a) response in the offspring.

METHODS

Pregnant NIH/OlaHsd females were immunized three times during pregnancy and one time postpartum with ovalbumin and the adjuvant Al(OH)3, and the offspring's ovalbumin-specific IgE, IgG1 and IgG2a responses were measured after challenge with the same allergen as young adults. Ovalbumin-specific IgE, IgG1 and IgG2a responses were also analysed in offspring of NIH/OlaHsd females immunized once at different times during pregnancy: about 3 days into pregnancy, mid-pregnancy (10 days into pregnancy) and about 4 days before giving birth (17 days into pregnancy).

RESULTS

Allergen immunization of mother during pregnancy and postpartum significantly reduced the IgE response in the progenies, whereas the IgG2a response to the same allergen was increased. Allergen immunization of the mother 3 days into pregnancy resulted in a significantly lower IgE response in offspring compared with the response in offspring of non-immunized mothers and in offspring of mothers immunized 17 days into pregnancy.

CONCLUSIONS

Maternal allergen immunization might favour selection for an allergen-specific Th1-dependent antibody response in the offspring. Our results indicate that IgE suppression is stronger after maternal allergen exposure during early pregnancy than after exposure in late pregnancy.

Leptin does not influence the IgE response to ovalbumin in mice

Leptin is important for maintenance of the body's energy homeostasis and it also increases Th1 and suppresses Th2 cytokine production. We have investigated the effect of leptin on the allergic immune response to the model allergen ovalbumin (OA) by using the popliteal lymph node assay (PLNA) and serum antibody determination in mice. Mice were injected with either leptin i.v. plus OA in one hind footpad, or leptin or OA alone. A booster dose of leptin was given twice and of OA once and the animals were exsanguinated on experimental day 19 when the PLNs also were removed. End-point measurements were serum levels of IgE, IgG1, and IgG2a anti-OA and weight and cell number of the excised PLNs. Leptin given i.v. with the protocol employed altered neither the cellular PLN response nor the specific serum IgE, IgG1, or IgG2a anti-OA levels compared with the group given OA without leptin. Our data indicate that systemic administration of leptin neither suppresses nor enhances the Th2-dependent antibody responses in the present mouse model.

Mycobacterium leprae and Mycobacterium lepraemurium infections in domestic and wild animals

Mycobacterium leprae, the aetiological agent of leprosy in humans, gives rise to a chronic granulomatous disease that affects primarily the skin and peripheral nerves, and secondarily some internal organs such as the testis and the eye; viscera are seldom involved. Depending on host resistance, leprosy may present as a benign disease (tuberculoid leprosy) or as a malignant disease (lepromatous leprosy), with a spectrum of intermediate stages appearing between the two. Immunity against leprosy depends on the cell-mediated immunity of the host, and this is severely compromised in the malignant (lepromatous) form of leprosy. Although culture of M. leprae has never been achieved in artificial media, the bacterium may be grown in several experimental animals, including the armadillo, non-human primates, and to a certain extent, rodents. Naturally acquired leprosy has been reported in wild nine-banded armadillos (Dasypus novemcinctus) and in three species of non-human primates (chimpanzees [Pan troglodytes], sooty mangabey monkeys [Cercocebus atys] and cynomolgus macaques [Macaca fascicularis]), thus qualifying leprosy as a zoonosis. Murine leprosy is a leprosy-like disease of rats and mice, caused by Mycobacterium lepraemurium. The disease affects primarily viscera and the skin, and very rarely peripheral nerves. Depending on the host strain, rodent leprosy may also evolve as 'lepromatous' or 'tuberculoid' leprosy, and strains of mouse that develop intermediate forms of the disease may exist. Growth of M. lepraemurium on conventional media for mycobacteria is not successful, but the bacterium has been cultured on an egg yolk-based medium. Naturally acquired murine leprosy has been observed in rats, mice and cats, but not in humans or any other species. Thus, in contrast to human leprosy, murine leprosy is not a zoonosis.

IgE adjuvant effect caused by particles - immediate and delayed effects

Diesel exhaust particles are reported to increase the specific IgE response to ovalbumin (OVA) and pollen. Evidence has been provided that the particle core contributes to this adjuvant activity. The purpose of our study was to investigate the effect of well-defined simple particles, polystyrene particles (PSP), on the production of allergen-specific IgE in a mouse model. The IgE adjuvant effect of PSP was investigated in experiments using intranasal (i.n.) instillation, intratracheal (i.t.) instillation or intraperitoneal (i.p.) injection. Delayed and cumulative adjuvant effects were investigated by giving mice i.p. injections with PSP 1-3 days, or on 4 consecutive days before OVA, respectively. The levels of allergen-specific and total IgE were measured. Irrespectively of immunisation route and protocol, OVA in combination with PSP elicited increased levels of both allergen-specific and total IgE when compared with OVA alone. Therefore, in the experimental model, particles were found to augment the specific IgE response to an allergen even when the allergen was introduced several days after the particles. These findings imply that individuals exposed to particulate air pollution at one point of time may develop an increased reaction towards allergens inhaled later that day or even several days after the particle exposure.

[Increased occurrence of allergy--is modern life style the cause?]

BACKGROUND

There is strong evidence that an increase in the occurrence of allergic diseases has taken place in industrialised countries over the last decades. The causes of this increase are unknown, but it seems to be linked to affluence and a modern, "westernized" lifestyle.

MATERIAL AND METHODS

Three international research papers are reviewed and discussed in the context of current knowledge of immunoregulatory effects from microbial and allergen exposure.

RESULTS

A German report indicates that early attendance (before one year of age) at daycare centres reduced the risk for allergy development in children from small, but not from large families. A Swiss and a Swedish paper report that children of farmers, or students attending anthroposophic Steiner schools had less allergic manifestations than their peers in the same local communities.

INTERPRETATION

The findings suggest that groups practising a somewhat simple, "old-fashioned" lifestyle within a modern community have a reduced risk of developing allergic diseases. Proper microbial stimulation of the immune system, possibly via the bacterial flora on the mucosal surfaces of the upper airways and the gut, may act to reduce the risk of becoming allergic. Insufficient microbial stimulation of the immune system may be a "deficiency disease" of modern society, leading to allergy.

Protective effect of Plantago major L. Pectin polysaccharide against systemic Streptococcus pneumoniae infection in mice

The antibacterial effect of a soluble pectin polysaccharide, PMII, isolated from the leaves of Plantago major, was examined in inbred NIH/OlaHsd and Fox Chase SCID mice experimentally infected with Streptococcus pneumoniae serotype 6B. Serotype 6B is known to give a more protracted infection when injected intraperitoneally into susceptible mice than more virulent serotypes like type 4. PMII was administered i.p. either once 3 days before challenge or once to thrice from 3 to 48 h after challenge. The number of bacteria in blood and the mouse survival rate were recorded. Pre-challenge administration of PMII and also lipopolysaccharide (LPS), included as a control, gave a dose-dependent protective effect against S. pneumoniae type 6B infection. However, injection of PMII after establishment of the infection in NIH/OlaHsd mice had no effect. The data demonstrate that, firstly, the polysaccharide fraction PMII from P. major protects against pneumococcal infection in mice when administered systemically prechallenge, and secondly that the protective effect is owing to stimulation of the innate and not the adaptive immune system.

The fungal cell wall component beta-1,3-glucan has an adjuvant effect on the allergic response to ovalbumin in mice

The polyglucose beta-1,3-D-glucan is a major structural component of the cell wall of yeasts and fungi. In the present study, the adjuvant activity of beta-1,3-glucan from the fungus Sclerotinia sclerotiorum (SSG) on the response to the model allergen ovalbumin (OA) was studied, using the popliteal lymph node assay (PLNA) in BALB/c mice. The adjuvant activity on the local cellular response was determined by measuring the weight, cell number, and proliferation of the extracted PLNs. The levels of OA-specific immunoglobulin (Ig)E, IgG1, and IgG2a in serum were measured by enzyme-linked immunosorbent assay (ELISA). Groups of 8 mice were given either SSG + OA, SSG alone, or OA alone on d 0. Thereafter they were exsanguinated on d 20, or reinjected with OA on d 21, before exsanguination on d 26 or 33. Only on d 26 was SSG + OA found to significantly increase the PLN weight and cell numbers, but not cell proliferation (thymidine incorporation), compared with OA or SSG alone. SSG + OA was also found to significantly increase both the anti-OA IgE and IgG1 levels on d 20, 26, and 33 compared to OA alone. Compared to SSG alone, SSG + OA increased the OA-specific IgE and IgG 1 levels significantly on d 26 and 33, but not on d 20. A similar increase was not found for IgG2a. Our results show that beta-1,3-D-glucan provides a clear Th2-dependent (allergic) immune response to OA, indicated by elevated levels of IgE and IgG1 and not IgG2a, in the mouse model used.

The adjuvant effect of particles-importance of genetic background and pre-sensitisation

BACKGROUND

We have previously reported that simple and well-characterised particles, such as polystyrene particles (PSP), have an IgE adjuvant effect in mice. The purpose of this study was to explore the importance of genetic background concerning the adjuvant effect of PSP in different strains of mice.

METHODS

Inbred NIH/Ola, BALB/c and C3H/HeJ mice were given two intraperitoneal injections with either PSP plus OVA or OVA alone, and then an intraperitoneal challenge with OVA alone. NIH/Ola mice were also pre-sensitised to develop a weak or strong IgE response to OVA, and then given an intraperitoneal challenge with PSP plus OVA or OVA alone. Serum levels of total and allergen-specific IgE and IgG2a were measured.

RESULTS

PSP had a specific IgE and IgG2a adjuvant effect in NIH/Ola mice but not in C3H/HeJ and BALB/c mice. Weakly pre-sensitised NIH/Ola mice showed the same response pattern as the naive NIH/Ola mice. In contrast, strongly pre-sensitised mice showed an antibody response pattern similar to that of high-responder BALB/c mice.

CONCLUSIONS

Our results indicate that the allergen responder status, either genetic or induced, is of importance for the adjuvant effect from particles. The IgE and IgG2a adjuvant effect may depend on the genetically determined susceptibility of an individual to be influenced by exposure to the adjuvant. Therefore, the allergy-enhancing effect from particle pollution may differ between individuals.

Intranasal immunization with heat-inactivated Streptococcus pneumoniae protects mice against systemic pneumococcal infection

In order to study the mucosal and serum antibody response to polysaccharide-encapsulated bacteria in mice, a preparation of heat-inactivated Streptococcus pneumoniae type 4 was administered, with and without cholera toxin, at various mucosal sites. It appeared that intranasal immunization of nonanesthesized animals was superior to either oral, gastric, or colonic-rectal antigen delivery with regard to the induction of serum immunoglobulin G (IgG) and IgA, as well as saliva IgA antibodies specific for pneumococci. The marked IgA antibody response in feces after intranasal, but not after oral or gastric, immunization is suggestive of a cellular link between the nasal induction site and the distant mucosal effector sites. Intranasal immunization also induced antibodies in serum and in mucosal secretions against type-specific capsular polysaccharide. IgA and IgG antibody levels in pulmonary lavage fluids correlated well with saliva IgA and serum IgG antibodies, respectively. Antibody determinations in pulmonary secretions may therefore be redundant in some cases, and the number of experimental animals may be reduced accordingly. After intraperitoneal challenge with type 4 pneumococci, mice immunized intranasally were protected against both systemic infection and death, even without the use of cholera toxin as a mucosal adjuvant. Thus, an efficient intranasal vaccine against invasive pneumococcal disease may be based on a very simple formulation with whole killed pneumococci.

Interleukin-13 and human immunoglobulin E production in severe combined immunodeficiency mice transplanted with human peripheral blood lymphocytes

As normal mice do not respond to interleukin-13 (IL-13), we have used mice with severe combined immunodeficiency transplanted with human peripheral blood lymphocytes (hu-PBL-SCID mice) as an in vivo model for studying human IL-13. PBL from three donors (two allergic and one non-allergic) were prestimulated with IL-13 in vitro and thereafter transplanted into SCID mice. As evidenced by flow cytometry, IL-13 in the in vitro cell cultures was physiologically active and suppressed CD14 expression, while it enhanced the expression of CD23 on human monocytes. In the in vivo experiments, SCID mice transplanted with cells from both allergic donors produced twice as high maximum levels of IgE when the cells were preincubated with IL-13 in vitro before transplantation, as compared with mice receiving cells that had not been preincubated with IL-13. Two succeeding intraperitoneal (i.p.) injections of IL-13 resulted in a further increase of maximum IgE levels. Using cells from the non-allergic donor, no enhancing effect of IL-13 was observed. Transplanted human cells from one allergic donor examined were shown to migrate to the spleen and lungs of the recipient mice, while cells from the non-allergic donor were found only in the peritoneal cavity. Altogether, our results indicate that IL-13 enhances human IgE production in vivo and suggest that lymphocytes in allergic individuals are hyper-reactive to this cytokine. Furthermore, the allergic status of the cell donor may affect migration and engraftment of cells transplanted into SCID mice.

Airborne house dust elicits a local lymph node reaction and has an adjuvant effect on specific IgE production in the mouse

Indoor suspended particulate matter (SPM) consists of many different types of particles, the vast majority of which are less than 2.5 microm in diameter. An important question is how these particles, being inhalable, contribute to asthma and respiratory symptoms. One possibility is that these particles have an adjuvant effect on the immune response and increase the IgE production, or cause a non-specific irritation in the airways, contributing to bronchial hyper-responsiveness. In this study, the adjuvant activity of indoor SPM on the response to the model allergen ovalbumin (OA) in BALB/c mice was investigated, using the popliteal lymph node (PLN) assay. The adjuvant activity on the local lymph node response was determined by measuring the PLN weight, cell numbers and cell proliferation, and the adjuvant activity on the IgE production by measuring the levels of serum IgE specific to OA. SPM was found to give a significant PLN response, both when injected alone and together with OA. SPM was also found to enhance the production of specific IgE to OA when injected together with OA, after reinjection with OA, compared with immunisation with OA alone.

Human IgE production in hu-PBL-SCID mice injected with birch pollen and diesel exhaust particles

Mice with severe combined immunodeficiency were transplanted with human peripheral blood lymphocytes (hu-PBL-SCID mice). The response to immunisation with birch pollen was used to study possible effects of diesel exhaust particles (DEP) and aluminium hydroxide (Al(OH)3) on human IgE production in this human in vivo model. The adjuvants were well tolerated, as determined by the number of human cells in the peritoneal cavity at the end of the experiments. Total and birch pollen-specific IgE was detected in 76 and 41% of the mice, respectively. In the present experiments where the mice were stimulated early with birch pollen, a doubling in percentage of hu-PBL-SCID mice with production of specific IgE was observed, as compared to later stimulation used in previous experiments. Although a tendency to higher total IgE levels was observed after treatment with DEP, no statistically significant adjuvant effect of DEP or Al(OH)3 could be demonstrated. Electron microscopy analysis after immunogold labelling showed that the major birch pollen allergen Bet v I was released from the pollen grains and adsorbed to the surface of the DEP. Early stimulation with allergen appears to be important for optimal production of specific IgE in the hu-PBL-SCID model. However, our results show that further improvements are needed in order to demonstrate the expected effects from adjuvants and environmental pollutants.

Protective effect of beta-glucan against mycobacterium bovis, BCG infection in BALB/c mice

Beta-1,3-glucan is a potent stimulator of macrophage functions and has a protective effect against a range of infections in rodent models. We examined whether the agent could also protect against the intracellular Mycobacterium bovis, bacillus Calmette-Guérin (BCG) infection in mice. BCG-susceptible BALB/c mice were injected intravenously (i.v.) with beta-glucan or vehicle 3 days before, or with beta-glucan 7 days after i.v. challenge with live BCG bacilli. The animals were killed 4 or 8 weeks later, their organs were homogenized and applied to object slides and stained with auramin for counting of bacilli, or seeded onto agar in Petri dishes. Mice treated with beta-glucan both pre- and postchallenge had significantly lower numbers of BCG bacilli and BCG colony-forming units in spleen homogenates compared with controls 4 weeks after challenge. A similar, but not statistically significant, tendency was observed in spleen homogenates from mice killed 8 weeks after challenge. In homogenates of liver and lungs there were similar findings, but less pronounced. There was a dose-dependent effect of beta-glucan injected before BCG challenge on the number of BCG bacilli found in spleen and liver homogenates. In addition, antibody cross-reactivity was demonstrated between M. tuberculosis cell wall and beta-glucan. The results suggest that beta-glucan has a protective effect against M. bovis, BCG infection in susceptible mice.

Diesel exhaust particles and carbon black have adjuvant activity on the local lymph node response and systemic IgE production to ovalbumin

The possible adjuvant effect of diesel exhaust particles (DEP) on the response to the model allergen ovalbumin (OA) was studied in BALB/c mice using the popliteal lymph node (PLN) assay. In addition to changes in PLN weight, cell numbers and cell proliferation, specific serum IgE anti-OA antibody levels were measured. OA inoculated together with DEP into one hind footpad gave a significantly augmented response (increase in weight, cell numbers and cell proliferation) in the draining popliteal lymph node as compared to DEP or OA alone. Also, the local lymph node response was of longer duration when DEP were given with the allergen. Experiments in thymus-deficient nu/nu mice indicated that the lymph node response observed in BALB/c mice was of a specific immunologic character and not an unspecific inflammatory reaction. The OA-specific IgE response was increased in mice receiving OA together with DEP as compared to the response in mice receiving OA without DEP. Carbon black (CB) was given with and without OA in some experiments, as a surrogate for the non-extractable core of DEP. CB was found to resemble DEP in its capacity to increase the local lymph node response and serum specific IgE response to OA, but CB appeared to be slightly less potent than DEP. Thus, both DEP and CB had a significant adjuvant effect on the local immune-mediated inflammatory response and on the systemic specific IgE response to allergen. The results indicate that the non-extractable particle core contributes substantially to the adjuvant activity of DEP.