Exposure levels of animal allergens, endotoxin, and β-(1,3)-glucan on a university campus of veterinary medicine

OBJECTIVES

The study aimed to determine the allergen, endotoxin and β-(1,3)-glucan concentrations at various areas on a university campus of veterinary medicine.

METHODS

Dust samples were collected four times a year for three years using electrostatic dust collectors (EDC) at 25 different locations on a campus of veterinary medicine and in laboratories of inorganic chemistry as a control area representing animal-free environment. Major animal allergens from dog, cat, horse, cattle and mouse, domestic mite (DM) allergens, and β-(1,3)-glucan were measured using enzyme immunoassays and endotoxin using the limulus amoebocyte lysate (LAL) assay. Seasonal, annual and local influences on exposure levels were analyzed using Bayesian mixed models.

RESULTS

With the exception of mouse allergens, all other determinants were found in almost all locations on the campus and in the control area, but in up to 10.000-fold variable concentrations. By far the highest levels of feline, canine, equine and bovine allergens were detected in buildings where the respective species were examined. The highest levels of mouse and DM allergens, β-(1,3)-glucan and endotoxin occurred together and were associated with locations where large animals were present. In buildings without animals, allergen levels were considerably lower but still elevated at several locations compared to the control area, especially for dog and horse allergens, and β-(1,3)-glucan. Significant seasonal effects were observed for dog, cat, horse and DM allergens, and β-(1,3)-glucan. Variations between years were less apparent than between seasons (except for β-(1,3)-glucan).

CONCLUSIONS

The strongest influencing factor on the concentration of mammalian allergens was the presence of the corresponding animal at the collection site. Seasonal influence on allergen concentrations was observed, while the overall exposure remained constant over the years. At locations with horses, elevated levels of mite allergens, endotoxin, and β-(1,3)-glucan can be expected, probably due to passive transfer from stable environment.

Comparing the concentration levels of allergens and endotoxins in employees' homes and offices

Objective

The aim of the study was to find out whether allergen and endotoxin concentrations in offices differ from those measured at the homes of employees, and identify the parameters that influence exposure.

Methods

Electrostatic dust collectors (EDCs) were placed in five office buildings (68 rooms, 436 EDCs), as well as the homes of the office workers (145 rooms, 405 EDCs) for 14 days, four times a year. In addition, surface samples were collected from the offices four times a year by vacuuming the carpeted floors. Domestic mite (DM), and the major cat and dog allergens (Fel d 1 and Can f 1) were quantified in all samples using fluorescence enzyme immunoassays. Endotoxin was measured in the EDC samples, using the Limulus amoebocyte lysate assay. The allergen and endotoxin concentrations were log transformed and analysed with multilevel models.

Results

Endotoxin concentrations were significantly higher in personal homes compared to levels measured in the offices, and depended on the number of persons living in each household, as well as the presence of a dog. DM allergens were significantly higher in households than in offices, and were significantly higher in bedrooms compared to living rooms. Offices occupied by cat owners had significantly higher Fel d 1 concentrations than offices or homes without. Additionally, Can f 1 concentrations were significantly higher in offices occupied by dog owners compared to those without.

Conclusions

Pet owners appear to transfer cat and dog allergens to their offices. Therefore, in case of allergy complaints at the office, employers and physicians might consider possible contamination by cat and dog allergens.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00420-021-01794-9.

Animal Allergens, Endotoxin, and β-(1,3)-Glucan in Small Animal Practices: Exposure Levels at Work and in Homes of Veterinary Staff

OBJECTIVES

In veterinary settings, high exposures to animal allergens and microbial agents can be expected. However, occupational exposure levels are largely unknown. The objective of this study was to estimate the allergen, endotoxin, and β-(1,3)-glucan concentrations in small animal practices and in the homes of practice employees.

METHODS

Dust samples were collected using electrostatic dust fall collectors in diverse rooms of 36 small animal practices, as well as in employees' homes. Major animal allergens (Fel d 1, Can f 1, Ory c 3, Cav p 1, Equ c 1, Bos d 2), domestic mite (DM) allergens, and β-(1,3)-glucan levels were measured using enzyme immunoassays. Endotoxin was determined using the Limulus amoebocyte lysate assay. Influences on exposure levels were analyzed using multilevel models.

RESULTS

The levels of Can f 1, Fel d 1, Ory c 3, and Cav p 1 were up to 30 times higher in practices compared with homes without animals, but significantly lower compared with the homes with the respective pet. Although horses were not treated in the practices, Equ c 1 was found in 87.5% of samples, with the highest concentrations measured in changing rooms. DM levels were significantly lower in practices than in all private homes, and endotoxin levels were similar to those in homes with pets. In the practice itself, exposure levels were significantly influenced by animal presence, type of the room, and area per employee; whereas, room volume and diverse cleaning measures had mostly no effect.

CONCLUSIONS

Exposure to animal allergens is high in veterinary practices, but it does not reach levels of households with pets. Domestic mite allergen and endotoxin exposure seem to be low for workers in veterinary practices. The high Equ c 1 detection rate strongly indicates dispersal of allergens, most likely through clothing and hair.

Analysis of inflammatory markers and metals in nasal lavage fluid of welders

Welding fumes may produce adverse health effects in the respiratory tract. To assess the relationship between exposure to welding fumes and inflammation in the upper airways, 190 male welders were examined from the WELDOX study (median age 40 yr, 54.7% smokers, and 32.9% atopics). Inhalable welding fumes were collected in the breathing zone of welders during a single shift. Chromium (Cr), nickel (Ni), manganese (Mn), and iron (Fe) were measured in the welding-fume samples and in postshift nasal lavage fluid (NALF). In addition, the numbers of particles and inflammatory biomarkers, including total and differential cell counts, interleukin (IL)-8, leukotriene (LT) B₄, 8-isoprostane (8-iso-PGF_2α), tissue inhibitor of metalloproteinase-1 (TIMP-1), and immunoreactive matrix metalloproteinase (MMP)-9, were determined. Metal concentrations in NALF correlated with airborne concentrations. No significant association was found between airborne metal concentrations and biomarkers of inflammation in NALF, whereas increasing metal concentrations in NALF resulted in increased concentrations of total protein, IL-8, MMP-9, and TIMP-1. LTB₄ and 8-iso PGF_2α were elevated at higher concentrations of Cr or Ni in NALF. The same was true for Fe, although the effects were less pronounced and of borderline significance. In conclusion, our results showed a significant association between the concentrations of metals and soluble inflammatory markers in the NALF of welders. The noninvasive collection of NALF is applicable in field studies, where it may serve as a suitable matrix to simultaneously assess biomarkers of exposure and effect in the upper respiratory tract in workers who are occupationally exposed to airborne hazardous substances.

Concentration of bioaerosols in composting plants using different quantification methods

BACKGROUND

Bioaerosols (organic dusts) containing viable and non-viable microorganisms and their metabolic products can lead to adverse health effects in exposed workers. Standard quantification methods of airborne microorganisms are mainly based on cultivation, which often underestimates the microbial burden. The aim of the study was to determine the microbial load in German composting plants with different, mainly cultivation-independent, methods. Second purpose was to evaluate which working areas are associated with higher or lower bioaerosol concentrations.

METHODS

A total of 124 inhalable dust samples were collected at different workplaces in 31 composting plants. Besides the determination of inhalable dust, particles, and total cell numbers, antigen quantification for moulds (Aspergillus fumigatus, Aspergillus versicolor, Penicillium chrysogenum, and Cladosporium spp.) and mites was performed. Concentrations of β-glucans as well as endotoxin and pyrogenic activities were also measured. The number of colony forming units (cfu) was determined by cultivation of moulds and actinomycetes in 36 additional dust samples.

RESULTS

With the exception of particle numbers, concentrations of all determined parameters showed significant correlations (P < 0.0001; r Spearman: 0.40-0.80), indicating a close association between these exposure markers. Colony numbers of mesophilic moulds and actinomycetes correlated also significantly with data of cultivation-independent methods. Exposure levels showed generally large variations. However, all parameters were measured highest in dusty working areas like next to the shredder and during processing with the exception of Cladosporium antigens that were found in the highest concentrations in the delivery area. The lowest concentrations of dust, particles, antigens, and pyrogenic activity were determined in wheel loader cabins (WLCs), which were equipped with an air filtration system.

CONCLUSION

It was possible to assess the microbial load of air in composting plants with different quantification methods. Since allergic and toxic reactions may be also caused by nonliving microorganisms, cultivation-independent methods may provide additional information about bioaerosol composition. In general, air filtration reduced the bioaerosol exposure shown in WLCs. Due to the fact that the mechanical processing of compost material, e.g. by shredding or sieving is associated with the generation of high bioaerosol concentrations, there is still a need of improved risk assessment and state-of-the-art protective measures in composting plants.

Ex vivo cytokine release and pattern recognition receptor expression of subjects exposed to dampness: pilot study to assess the outcome of mould exposure to the innate immune system

In rooms with moisture damage, the indoor air can be enriched with microorganisms causing a variety of symptoms. Due to the highly diverse composition of bioaerosols and the multiple effects on humans, an assessment of the health risk is not sufficiently possible. The aim of this study was to characterize the features of innate immunity using blood from subjects exposed to moisture damage compared to control subjects living in houses without visible moisture damage. We investigated the expression of TLR-2, TLR-4 and dectin-1 on the surface of monocytes from both fresh blood and after in vitro stimulation with the model substances E. coli endotoxin, zymosan A, Pam3Cys and Aspergillus versicolor in 25 exposed subjects and 25 control subjects. In vitro stimulation of whole blood with the same components was performed for 20 h and the release of inflammatory mediators IL-8 and IL-1β were quantified. In addition to an enhanced number of blood leucocytes, the expression of the receptors TLR-2, TLR-4 and dectin-1 on blood monocytes was significantly enhanced in exposed subjects. In contrast, no different alteration in expression was detected between exposed and control group after in vitro stimulation with the model substances. The release of IL-8 and IL-1β after stimulation of whole blood with A. versicolor was increased in subjects exposed to moisture damage. Furthermore, in the exposed subjects the IL-1β release was significantly enhanced after in vitro stimulation with E. coli endotoxin (1000 pg/mL). In conclusion, features of the innate immune system (receptor expression and mediator release of monocytes) are altered in subjects exposed to moisture damage which may be a potential explanation for the increased incidence of respiratory health diseases observed in these populations.

Assessment of airborne exposure to endotoxin and pyrogenic active dust using electrostatic dustfall collectors (EDCs)

Passive airborne dust sampling using electrostatic dustfall collectors (EDCs) is one possibility especially for long sampling periods. In this study, EDCs were deposited in living rooms of private households and in social rooms of composting plants. The aim of the study was to determine whether endotoxin and pyrogenic activity are measurable using EDCs. In all extracts, endotoxin (via Limulus amebocyte lysate [LAL] assay) and pyrogenic activity (interleukin [IL]-1β release via whole blood assay) were detectable. In addition, the monocyte chemotactic protein (MCP-1; CCL-2) as a secondary proinflammatory marker was measured with whole blood assay. Endotoxin activity and proinflammatory/pyrogenic activity of EDC extracts from social rooms in composting plants were higher compared to extracts obtained from EDCs in private household rooms. A significant correlation between LAL assay and whole blood assay was detectable. In conclusion, EDC sampling is an applicable method to evaluate settled dust from airborne bioaerosols displaying a longer period of exposure. The extraction of EDC without Tween enables one to measure endotoxin as well as proinflammatory/pyrogenic activity using the same sample for parallel detection and more reliable characterization of the airborne bioaerosol contamination.

Standardization of whole blood assay for determination of pyrogenic activity in organic dust samples

To characterize bioaerosol exposure at workplaces standardized methods are necessary. Activity of endotoxin, one component of organic dust, can be quantified with the Limulus-Amoebocyte Lysat test (LAL test). Further information with respect to pyrogenic activity of the organic dust can be achieved by measuring cytokine release of human blood after stimulation with the dust or its extract (whole blood assay). The aim of our study was the standardization of the whole blood assay (WBA) while using cryo-preserved human blood (Qualis Laboratorium) and to compare the outcome of the different cytokines determined by incubation of the blood cells with extracts from dust samples collected at various workplaces. Cytokine release (IL-1 beta, IL-6, IL-8, TNF-alpha, MCP-1) was measured by ELISA after stimulation of fresh blood from ten donors as well as cryo-preserved human blood. In both cases blood was stimulated with E. coli endotoxin as well as with 30 dust filter extracts from various workplaces. All dust filter extracts were investigated in the WBA using cryo-preserved blood as well as with LAL test. E. coli endotoxin stimulated the release of IL-1 beta, IL-6, IL-8, TNF-alpha and MCP-1 in a dose-dependent manner in fresh as well as cryo-preserved human whole blood. 200 pg/ml E. coli endotoxin induced maximal cytokine release in cryo-preserved blood (mean value for IL-1 beta 2509+/-418 pg/ml; n=13 experiments) whereas fresh blood of single donors reached a maximum release when stimulated with 50 ng/ml endotoxin (mean value of ten donors 1125+/-553 pg/ml IL-1beta). Using cryo-preserved blood the coefficient of variation (CV) regarding the interassay variability was below 21% for all cytokines measured. Regarding 26 dust sample extracts correlation coefficient r2 for LAL test and WBA was between 0.90 and 0.93 (Pearson) for IL-1 beta, IL-6, IL-8 and TNF-alpha whereas correlation for MCP-1 was lower (r(2)=0.59). Two dust sample extracts which showed similar reactivity patterns in LAL test as well as in WBA with respect to IL-1 beta, IL-6, IL-8 and TNF-alpha could be differentiated by measuring MCP-1. In conclusion, cryo-preserved blood pools are suitable to standardize WBA. Combination of different outcome variables like IL-1 beta and MCP-1 improve the characterization from the inflammatory potency of workplace related dust samples.

Evaluation of quantification methods of occupational endotoxin exposure

Endotoxin has been identified as important component of organic-dust exposure and is suspected as main cause of work-related adverse health effects in dusty areas. Although the determination of endotoxin levels by using the Limulus amoebocyte lysate (LAL) assay is internationally accepted, reliability and variation of values measured with this test remain a point of discussion. Therefore, the purpose of the study was to determine the influence of different parameters on endotoxin activity measured in airborne samples. This study thus analyzed: (a) dust filter extraction procedures, (b) storage of samples, (c) usage of different commercially available LAL assays, and (d) results of the whole blood assay (WBA) compared to the LAL test. Using a parallel sampler, 120 filters were loaded with dust at 4 different occupational settings and extracted in 2 labs using a standardized protocol. Parameters like Tween in the extraction medium, extraction volume, centrifugation speed, and material of tubes used for extraction were tested. The LAL test and the WBA were able to determine the differences in dust load of filters obtained from the settings investigated. In addition, results varied significantly with modifications in extraction procedures. Using Tween for filter extraction mainly influenced the resulting endotoxin activity. In addition, LAL test differences according to manufacturer of LAL test, extraction volume, and whether the samples are freshly processed or frozen also resulted in significant variations in the endotoxin levels. In conclusion, a reliable assessment of exposure to endotoxin activity is only possible if standard operation procedures (SOPs) for sampling and determination are established.

Occupational endotoxin-exposure and possible health effects on humans

BACKGROUND

Endotoxins are commonly found at workplaces where large amounts of bioaerosols are generated. In Germany, especially since the Ordinance on Safety and Health Protection related to work involving biological agents (Biostoff-Verordnung) became effective (1999), threshold limit values are widely discussed. Up to the present, endotoxin values are measured with non-uniform methods and therefore values are of limited benefit for classification of exposure groups. In Germany there is no threshold limit value for endotoxin.

METHODS

Relevant literature of the last 20 years was selected from Medline and discussed.

RESULTS

In this review we focused on the impact of endotoxin exposure on human health with special respect to the measurements on workplace and methodological aspects of endotoxin determination. Methods for sampling and endotoxin determination have to be validated, optimized, and standardized first.

CONCLUSION

The adverse health effects of endotoxins are known, standardization of measurements is a necessary goal and protection measures should be established immediately.

Does IL-4 play a role in the expansion of V beta 8a T cell receptor-bearing cells?

BACKGROUND

Peripheral blood mononuclear cells (PBMC) of subjects allergic to the insect-derived allergen Chi t 1--9 are characterized by an allergen-induced pronounced proliferation and increased expression of activation markers (CD25, HLA-DR, CD23). T cell lines showed an elevated percentage of V beta 8a-positive cells following stimulation by Chi t 1--9.

OBJECTIVE

The aim of the present study was to investigate whether V beta 8a dominance plays an important role in PBMC short-term cultures (24 h) as well. The role of exogenous added cytokines, especially IL-4, has been determined.

METHODS

The T cell receptor repertoire was measured with 16 monoclonal antibodies to epitopes on the variable region of the beta chain by flow cytometry. Patients allergic to Chi t 1--9 were compared to nonallergic subjects as well as to subjects with other occupational allergies. In addition, cytokines were determined intracellulary by flow cytometry. Studies were performed with PBMC cultured for 24 h.

RESULTS

After cultivation for 24 h without or with different stimuli (cytokines, allergen, phytohaemagglutinin), changes in the T cell receptor profile and the cytokine profile were measurable compared to the baseline value (without cultivation). Stimulation with IL-4 revealed increased percentages of V beta 8a-expressing cells in Chi t 1--9-sensitized patients. This IL-4-induced V beta 8a increase did not occur in PBMC from the two control subject groups (non-allergic and allergic to other allergens than Chi t 1--9). CONCLUSION In conclusion, the dominance of certain T cell receptor types seems to arise due to the exposure to specific allergens and cytokine production. Some T cell receptors are often affected, for example V beta 8a, whereas others only show minor variations. V beta 8a expression obviously plays an important role in Chi t 1-9 allergy.

B-cell epitopes of the allergen Chi t 1.01: peptide mapping of epitopes recognized by rabbit, murine, and human antibodies

BACKGROUND

Chi t 1.01, a hemoglobin of the midge Chironomus thummi thummi, is a widespread environmental and occupational allergen. The aim of the present investigation was to identify and compare peptides involved in B-cell epitopes of Chi t 1.01 recognized by 15 human IgE sera, six murine monoclonal antibodies (mAbs), and a polyclonal rabbit antiserum.

METHODS

Synthetic peptides 19-21 amino acids long covering the whole Chi t 1.01-sequence were covalently coupled to activated paper disks as well as adsorbed to wells of immunoplates and used for enzyme-linked immunosorbent assay. For fine epitope mapping, we used overlapping synthetic octapeptides with one amino-acid offset.

RESULTS

Peptides containing the amino acids 13-17, 23-29, and 40-50 were recognized by three of the mAbs, while three other mAbs reacting with none of the peptides obviously recognized conformational epitopes. Binding sites for rabbit antibodies and for human IgE antibodies were scattered over the whole molecule. The peptide 80-100 seemed to comprise at least one important IgE epitope. Depending on the method of antigen binding to the solid phase, differing results were obtained.

CONCLUSIONS

Several linear epitopes in Chi t 1.01 are recognized by human IgE antibodies, by mAbs, and by polyclonal rabbit antibodies. In addition, the results indicate the presence of conformational epitopes.

T-cell receptor repertoire expression in workers with occupational asthma due to platinum salt

There is a high incidence of asthma, rhinitis, conjunctivitis and contact urticaria in workers of precious metal refineries. Symptoms are closely associated with sensitization to halogenated platinum compounds, as assessed by skin-prick test. The aim of the present study was to examine the molecular mechanisms involved by describing the T-cell receptor (TCR) repertoire distribution of peripheral blood mononuclear cells (PBMCs) without and after in vitro stimulation with sodium hexachloroplatinate. PBMCs of 17 sensitized subjects with work-related asthma and a positive skin-prick test result to sodium hexachloroplatinate and of 15 nonexposed subjects were isolated and TCR expression determined by flow cytometry. Furthermore, the sodium hexachloroplatinate-mediated in vitro effects on the frequency of Vbeta-expressing T-cells, the proliferation response and the expression of cell surface molecules like CD71, CD25, CD95 and HLA-DR were studied. CD3-positive lymphocytes of platinum salt-sensitized workers had a significantly higher frequency of Valpha2a+, Vbeta11+ and Vbeta21.3+ T-cells than controls (p<0.01, p<0.01 and p<0.001 respectively). In vitro stimulation of PBMCs from platinum salt-sensitized as well as control subjects with sodium hexachloroplatinate increased the percentage of CD3-positive cells bearing specific TCRs, especially Vbeta5.3, Vbeta6.7, Vbeta8a, Vbeta20 and Vbeta21.3. This effect was time- and dose-dependent. The present results indicate that the frequencies of Valpha2a-, V11 and Vbeta21.3-bearing blood T-cells and platinum salt-induced lymphocyte proliferation are strongly enhanced in subjects who suffer from asthma due to platinum salt. In addition, in vitro stimulation with sodium hexachloroplatinate modulates the frequencies of certain T-cell receptor-bearing T-cells.

Exposure-response relationships of occupational inhalative allergens

Only a few threshold limit values exist at present for allergens in the workplace known to cause bronchial asthma. This contrasts with the great number of occupational asthma cases observed in industrialized countries. Recently published studies provide clear evidence for exposure intensity response relationships of occupational allergens of plant, microbiological, animal or man-made origin. If allergen exposure levels fall short of determined limit values, they are not associated with an increased risk of occupational asthma. Corresponding data are available for wheat flour (1-2.4 mg/m3), fungal alpha-amylase (0.25 ng/m3), natural rubber latex (0.6 ng/m3), western red cedar (0.4 mg/m3) and rat allergens (0.7 microg/m3). It is suggested to stipulate legally binding threshold limit values (TLV/TWA) on this basis in order to induce more effective primary preventive measures. If no reliable data on the health risk of an occupational airborne noxa exist, the lowest reasonably practicable exposure level has to be achieved. Appropriate secondary preventive measures have to be initiated in all workplaces contaminated with airborne allergens. Verified exposure-response relationships provide the basis for risk assessment and for targeted interventions to reduce the incidence of occupational asthma also in consideration of cost benefit aspects. 'Occupational asthma is a disease characterized by variable airflow limitation and/or airway hyperresponsiveness due to causes in a working environment. These causes can give rise to asthma through immunological or non-immunological mechanisms. Up to 15% of all asthma cases are of occupational origin or have at least a significant causal occupational factor. According to the New Zealand part of the European Respiratory Health Survey, an increased risk of asthma prevalence was found for several occupations such as laboratory technicians, food producers, chemical workers, plastic and rubber workers. The Spain part of this study comprising 2646 Spanish subjects showed an asthma risk to be attributed to occupational exposures between 5 and 6.7%. Main asthma-inducing agents in the workplace are flour, grain and feed dust, animal dander/urinary proteins and isocyanates. Further, several inhalative irritants such as chlorine, acid or alkaline aerosols play a pivotal role. Many low molecular weight chemicals have irritative as well as allergenic effects on the airways, e. g. isocyanates and acid anhydrides. In addition to chronic or repetitive exposures, also singular accidental exposure to high concentrations of irritative or toxic airborne substances can cause occupational asthma. This condition is frequently called reactive airways dysfunction.

Analysis of T-cell reactive regions and HLA-DR4 binding motifs on the latex allergen Hev b 1 (rubber elongation factor)

BACKGROUND

The rubber elongation factor in Hevea rubber (Hev b 1) is one of the important latex-allergenic proteins inducing the production of specific IgE antibodies in latex-exposed subjects. In addition, Hev b 1 induces lymphocyte proliferation responses. A study about detailed T-cell epitope analysis of major latex allergens has not been published yet.

OBJECTIVE

The aim of this study was to define the T-cell reactive regions on the latex allergen Hev b 1.

METHODS

Nine overlapping peptides with 19 or 17 amino acid lengths representing the complete sequence of Hev b 1 were used for T-cell epitope mapping. Peripheral blood mononuclear cells (PBMCs) of latex-sensitized patients and healthy subjects were isolated and stimulated with the synthetic peptides to determine the specific proliferation response. The examined patients were sensitized to latex by occupational exposure (n=14) and suffered from rhinitis, conjunctivitis, contact urticaria and/or asthma. Two control groups of non-sensitized subjects were studied, one occupationally exposed to latex (n=4), the other one not exposed to latex (n=4).

RESULTS

Positive proliferation response induced by one or more peptides was detected in 10 of the latex-sensitized patients and in two of the latex-exposed non-sensitized subjects. Each patient exhibited an individual epitope reactivity pattern. The whole protein was found to be immunogenic, but the intensity of lymphocyte responses induced by the peptides was different. The majority of the patients' PBMCs (more than 66%) responded to the peptides 31-49 and 91-109. Using the peptide selection of Stille's algorithms, three epitopes were predicted covering region 38-74 and two others covering region 82-104; the two peptides 31-49 and 91-109 are part of these regions. A strong HLA-DR4Dw4 (DRB1*0401)-binding motif according to published DR4w4 binding motifs was predicted in the region of 102-110 including peptide 91-109 to which the majority of tested HLA-DR4-positive patients responded.

CONCLUSIONS

Our data indicate that the whole 14 kDa protein Hev b 1 is immunogenic having regions that demonstrate individual and varying PBMC stimulation. Experimental data of T-cell reactive regions based on PBMC-stimulation complement the information on T-cell epitope prediction. In addition, the Hev b 1 molecule contains a HLA-DR4Dw4 (DRB1*0401)-binding motif.

Flow-cytometric analysis of T-cell receptor expression in peripheral blood lymphocytes

BACKGROUND

Lymphocytes of subjects sensitized to the insect-derived allergen Chi t 1-9 are, in response to the allergen, characterized by an elevated proliferation and increased expression of activation markers such as HLA-DR and CD25 in vitro. A restriction for HLA-DR B1 in monosensitized patients was found.

OBJECTIVE

The aim of this study was to investigate whether the response to the allergen Chi t 1-9 involves the preferential cell surface expression of a specific alpha/beta T-cell receptor type.

METHODS

The T-cell receptor repertoire was measured with 7 monoclonal antibodies to epitopes on the variable region of the alpha- and beta-chain by flow cytometry. Cell lines of 9 patients were established with Chi t 1-9, 6 with tetanus toxoid and 6 with phytohaemagglutinin in the presence of interleukin 2. In addition, non-stimulated lymphocytes as well as lymphocytes of 5 non-sensitized controls exposed to Chi t 1-9 were examined.

RESULTS

Each of the 9 sensitized and 5 control subjects studied showed an individual pattern of lymphocyte expression for each T-cell receptor specificity. However, after stimulation specific to Chi t 1-9 for 2 weeks, a significant increase in V beta 8-expressing cells was measurable only in patients sensitized to Chi t 1-9. The cells of the 5 control subjects showed no significant changes due to the allergen stimulation.

CONCLUSION

These data suggest that the expression of certain T-cell receptor types plays an important role in the development of Chi t 1-9 allergy.

Lymphocyte proliferation response to extracts from different latex materials and to the purified latex allergen Hev b 1 (rubber elongation factor)

BACKGROUND

Type I allergy to latex is a growing problem, especially among health care workers. A detailed study of the peripheral blood cell responses to latex allergens has not been reported.

METHODS

Peripheral blood mononuclear cells of patients and healthy subjects were isolated and stimulated with protein extracts from latex sap and latex gloves and the purified latex allergen Hev b 1 (rubber elongation factor) at different concentrations to determine the antigen-specific proliferation response. The examined patients were sensitized to latex by occupational exposure (n = 23) and had rhinitis, conjunctivitis, contact urticaria, and/or asthma. Two control groups of nonsensitized subjects were studied: one occupationally exposed to latex (n = 8), and the second, not exposed to latex (n = 8).

RESULTS

In general, only latex-exposed subjects responded to the different latex antigen preparations. Lymphocyte proliferation responses to latex sap extract were found in 65% of latex-sensitized subjects and in 37.5% of the latex-exposed healthy subjects. Latex glove extract induced a significant proliferative responses in 47.8% of latex-sensitized patients and in 25% of the latex-exposed individuals. Hev b 1 induced lymphocyte proliferation responses in 52% of the latex-sensitized patients and in 25% of the latex-exposed subjects indicating that Hev b 1 is relevant antigen in these latex-sensitized and latex-exposed groups. Peripheral blood mononuclear cells of 39.1% of the latex-sensitized subjects responded to all three allergen preparations (latex sap and latex glove extract, as well as Hev b 1). We could find no correlation between latex-specific IgE level and latex-induced lymphocyte proliferation response.

CONCLUSION

Our data indicate that the 14 kd protein Hev b 1 is a relevant allergen in health care workers. It can be detected by specific IgE antibodies to Hev b 1, as well as in lymphocyte proliferation assay. In addition, our study suggests that antigen-specific proliferation response to latex is associated with exposure to latex, but not with the level of specific latex IgE. This may be useful for the evaluation and prediction of latex hypersensitivity development.

Analysis of B-cell epitopes in the N-terminal region of Chi t I component III using monoclonal antibodies

The hemoglobins of the midge Chironomus thummi thummi (Chi t I) are known to cause immediate-type hypersensitivity reactions in humans. Further knowledge of the antigenic sites of such allergens will provide new therapeutic approaches. The aim of our study was to identify and characterize linear B-cell epitopes of the hemoglobin component III of Chi t I (136 amino acid residues). Using the antigenic index algorithm of Jameson and Wolf (Jameson and Wolf (1988) Comput. Appl. Biosci. 4, 181-186), three linear binding sequences of this allergen molecule were predicted. Two mouse monoclonal antibodies (mAbs 3 and 6) raised against purified Chi t I component III were investigated by ELISA for their binding to nine synthetic peptides 19-21 residues in length, covering nearly the whole sequence of component III. MAb 6 recognized only one peptide (11-30) while mAb 3 bound to both N-terminal peptides (1-19 and 11-30), suggesting that the antibody binding site is located in the overlapping region. This assumption could be confirmed in ELISA with solid phase-bound recombinant peptides (RP) as well as in inhibition studies with free tryptic peptides indicating that identification of these linear B-cell epitopes is neither influenced by the method of peptide production nor by the kind of used immunoassay. To define the essential amino acid residues we investigated mAbs with solid phase-bound overlapping octamers. In the case of mAb 3, amino acids experimentally identified as essential for antibody binding (aa 13-17) are identical with those residues predicted as a B-cell epitope with the antigenic index of Jameson and Wolf.

Conformations of peptide fragments comprising the complete sequence of component III of Chi t I and their relationship to T-cell stimulation

Conformational preferences of synthetic peptides that span the complete sequence of Chironomus thummi hemoglobin (Chi t I) component III were studied by nuclear magnetic resonance (NMR) and CD spectroscopies. The peptides, 19-21 amino acids in length, were studied in water, except for the C-terminal peptide, which was investigated in DMSO-d6. NMR showed that all investigated peptides lacked uniquely folded conformations in water at 4 degrees C and pH 3.0 or at 10 degrees C and pD 6.6 in DMSO. However, some preferential helix-like conformations for the peptides corresponding to the helices of the folded protein could be seen in solution. These peptides showed characteristic interactions for conformations in both the beta- and alpha-regions of phi-psi space, based on strong C alpha H(i)-NH(i + 1) interactions, and on NH-NH, C alpha H(i)-NH-(i + 2), C alpha H(i)-NH(i + 3), and C alpha H(i)-C beta H(i + 3) interactions, respectively. Helical motifs seem not to be the most important factors in determining MHC-binding and/or T-cell recognition. However, there is a tendency that more stabilized secondary structures show higher T-cell stimulation.

Allergen-induced expression of cell surface markers on lymphocytes of Chi t I-sensitized patients

Lymphocyte cultures of persons sensitized to the hemoglobin allergen Chi t I show a highly significant response to the allergen measured in the lymphocyte stimulation assay by (3H)-thymidine uptake. In this study, we investigated by flow cytometry the expression of different cell surface markers on lymphocytes after in vitro stimulation for 7 d with or without the allergen Chi t I. We determined the expression of the low-affinity receptor for IgE (CD23) on lymphocytes of Chi t I-sensitized patients and Chi t I-exposed as well as nonexposed controls. CD23 expression was significantly higher in patients than in nonexposed controls. Exposed but healthy subjects showed intermediate values. We also determined the expression of activation markers CD25 (IL-2 receptor) and HLA-DR on the lymphocytes of patients and nonexposed controls. HLA-DR expression on non-T cells (CD3-) was significantly higher in patients than in controls. HLA-DR on T cells (CD3+), and CD25 as well as CD23 expression, could be significantly enhanced after antigen-specific stimulation in patients but not in controls, whereas alpha/beta-T-cell-receptor expression was significantly reduced in patients. Differences between patients and controls were not observed in response to tetanus toxoid (TT) and phytohemagglutinin (PHA). Our results demonstrate antigen-specific influences on the expression of cell surface molecules. These findings may be valuable diagnostic information.

Increased gamma/delta-positive T-cells in blood and bronchoalveolar lavage of patients with sarcoidosis and hypersensitivity pneumonitis

A small population of T-cells does not express the conventional T-cell receptor (TCR), characterized by the alpha and beta polypeptide chains (alpha/beta TCR) but two polypeptides termed gamma and delta (gamma/delta TCR). Changes in gamma/delta TCR expression may be relevant as the cause or consequence of several diseases. Our study was undertaken to determine and compare the distribution of T-cells expressing gamma/delta TCR in blood and bronchoalveolar lavage (BAL) of patients with sarcoidosis, hypersensitivity pneumonitis (HP), idiopathic pulmonary fibrosis (IPF), and of healthy controls. In addition, the association between gamma/delta TCR of blood T-lymphocytes and accessory molecules was analysed. Using direct immunofluorescence with the anti-gamma/delta TCR and anti-CD3 monoclonal antibodies (MoAbs) followed by flow cytometric analysis, the blood of patients with pulmonary sarcoidosis, HP, IPF and of healthy controls was analysed. To reveal the association between gamma/delta TCR of blood T-lymphocytes and the accessory molecules, expression of CD4, CD8 and CD25 were determined. Calculating the percentage and the total number of CD3+ gamma/delta TCR cells in blood, the data indicated a significant increase of gamma/delta T-cells in individuals with pulmonary sarcoidosis and HP, compared to healthy controls and IPF patients. In sarcoidosis patients with elevated CD3+ gamma/delta TCR levels, significantly lower CD4/CD8 ratios were observed. In addition, our data demonstrate a correlation between the decrease of CD4+ cells in blood and the amplified appearance of gamma/delta TCR expression in sarcoidosis patients, but not in HP patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Chironomidae hemoglobin allergy in Japanese, Swedish, and German populations

Hemoglobins of the Diptera (insect) family Chironomidae have been identified as causative allergens in asthmatic patients. In this study, 229 Japanese, 17 Taiwanese, and 92 Swedish sera from atopic patients were tested for antibodies against Chi t I, the hemoglobin from the European midge species Chironomus thummi, and against crude extracts from the Japanese midges Tokunagayusurika akamusi (T. akamusi) and Cricotopus sylvestris (Cr. sylvestris). Nearly 40% of patients showed a positive reaction to Cr. sylvestris extract, which contains no hemoglobin. This result is probably due to the presence of other partially cross-reacting allergens than hemoglobin. Nearly all tested Japanese serum samples showed cross-reactivity between Chi t I and Cr. sylvestris, a finding which is evidence for common epitopes in both midge species. Furthermore, an overall good correlation between the amounts of IgE antibodies against Chi t I and Chi t I component III was found in sera from Swedish, Japanese, and German patients.

Epitope mapping with peptides of Chi t I component III and immunomodulation of the Chi t immune response

BACKGROUND

Hemoglobins of the Diptera family are known as aggressive inhalant allergens.

METHODS

The whole sequence of the insect allergen Chi t I component III was studied for T-cell epitope activity in cell cultures of 15 sensitized patients with a panel of 17 overlapping synthetic peptides and 12 peptides obtained by tryptic cleavage.

RESULTS

All but one of the peptides tested were found to be immunogenic. The nonstimulatory sequence 102-109 and two other tryptic peptides (69-90 and 110-135) were used in inhibition experiments. The Chi t I-induced proliferation was downregulated by all tested peptides when compared with stimulation with Chi t I alone.

CONCLUSIONS

Because stimulation with phytohemagglutinin or tetanus toxoid was not influenced by the above-mentioned peptides, this mechanism seems to be specific for the antigen. Specific immunomodulation with nonstimulating peptides may offer new therapy approaches.

Humoral immune response to the insect allergen Chi t I in aquarists and fish-food factory workers

Our examination of 225 subjects who had been exposed to the insect allergen Chi t I involved the degree of allergen exposure, the exposure-associated symptoms, and their relationship to the presence of specific IgE and IgG antibodies as well as sensitization to ubiquitous allergens. It could be shown that specific IgE antibodies found in 34% of these subjects were closely associated with symptoms (P < 0.01), whereas no relationship between IgG antibodies and complaints could be observed. Conjunctivitis (63%) and rhinitis (62%) were predominant, followed by asthma (45%) and urticaria (37%). Antibody levels of patients suffering from asthma were highest. In addition, symptoms were associated with the degree of exposure. While nearly all IgE-sensitized subjects of the medium-, high-, and very high-exposure group were symptomatic, only 57% of the sensitized individuals of the low-exposure group reported complaints. Furthermore, specific IgE antibodies were most frequently present in the groups with medium (46%) and high (54.5%) exposure, whereas IgG antibodies predominated in individuals with very high exposure (69.1%). In the low-exposure group, most subjects (73.6%) had neither IgE nor IgG antibodies. In addition, within Chi t I sensitized subjects, sensitization to common allergens and elevated total IgE levels were more frequently present than within non-Chi t I sensitized individuals, indicating a predisposition to allergy.

Insect hemoglobins (Chi tI) of the diptera family Chironomidae are relevant environmental, occupational, and hobby-related allergens

Six hundred and forty-two persons with hobby-related (n = 205), occupational (n = 85), or environmental contact (n = 352) to the midge and larval allergen Chi tI were studied. Frequencies of IgE-mediated sensitization in these selected populations were 36.1%, 24.7%, and 9.6% respectively. Occupationally sensitized subjects who had been heavily exposed showed higher levels of antibodies, were more frequently diagnosed as having bronchial asthma and less frequently as having conjunctivitis, and had a significantly shorter latency period when compared to environmentally exposed people or aquarists. Our results are evidence for a higher risk of sensitization and of bronchial asthma in highly exposed subjects.

[Aquarium--when hobby becomes a danger. A case report]

In this case report, allergic rhinitis and episodes of asthma triggered by the hemoglobin of the red mosquito larva used as fish food are described. After three years of contact and an allergic condition persisting for three months, skin testing and IgE determination revealed moderate sensitization of the immediate reaction type. When contact with the allergen was stopped, the symptoms abated immediately.

Immunological cross-reactivity of hemoglobins in the Diptera family Chironomidae

Polyclonal human IgE antibodies of patients sensitized to one species of the Diptera family Chironomidae as well as polyclonal rabbit anti-Chi t I hyperimmune serum recognize antigenic sites present in nearly all of the 33 species of this insect family. Evolutionary distantly related genera usually show weaker antibody binding. According to the pattern of reactivity of rabbit anti-Chi t I-component III, expression of the epitopes of this molecule varies considerably in the genera Chironomus and Glyptotendipes; it appears to be almost totally absent in all other species. Of five monoclonal antibodies raised against Chi t I-component III, two recognize an epitope which is expressed in nearly all closely related species. Three monoclonal antibodies recognize epitopes which are expressed in only a few species of the same genus. Our results demonstrate the presence of common as well as species-specific epitopes in chironomid hemoglobins which behave as potent inhalant allergens.

Stimulation of human peripheral blood lymphocytes with chironomid hemoglobin allergen (Chi t I)

Hemoglobins (Chi t I) of the dipteron species Chironomus thummi thummi are known to cause severe allergic diseases in humans. We tested the allergen-specific stimulation of human peripheral blood lymphocytes (PBL) by Chi t I and its nine main components. Further, we applied fragments of the well-analyzed component III, obtained by cleavage with trypsin as well as arginine protease. In this way, we screened the molecule in order to identify T-cell epitopes. The whole component was found to be immunogenic and to have regions demonstrating varying PBL stimulation. In addition, interindividual patterns of reactivity, probably due to genetic restriction, were found. A T-cell epitope could be shown to be within the site 98-111, as predicted by application of Rothbard's algorithms.