Mite and cat allergen exposure in Brazilian public transport vehicles.

BACKGROUND: Mites and pets are important sources of indoor allergens. OBJECTIVES: To determine Dermatophagoides pteronyssinus (Der p 1), Dermatophagoides farinae (Der f 1), and Felis domesticus (Fel d 1) allergen levels in buses and taxis and to evaluate the predominant allergen in each vehicle type. METHODS: Mite and cat allergens were measured using enzyme-linked immunosorbent assay in dust samples collected from upholstered seats in 60 natural-ventilation buses (NVBs), 60 artificial-ventilation buses (AVBs), and 60 taxis. Thirty dust samples from AVB air-conditioning filters were also included. RESULTS: Levels of Der p 1 and Der f 1 were significantly higher in AVBs than in NVBs, whereas Fel d 1 levels were not significantly different between bus types. No significant differences were found in mite allergen levels in various sites in both types of buses, whereas Fel d 1 levels were significantly higher in rear and middle seats than in front seats in NVBs. Mite and cat allergen levels in taxis were significantly higher in passenger's rear seats than in driver's seats. A high proportion of dust samples from the vehicles, especially AVBs (82% for Der p 1 and 58% for Der f 1) had sensitizing levels of mite allergens, whereas more than 60% of samples from all vehicles had sensitizing levels of Fel d 1 allergen. In AVBs, samples from seats showed significantly higher levels of mite and cat allergens than those from air-conditioning filters. CONCLUSIONS: Public transport vehicles constitute an important allergen reservoir for continuous contamination of the indoor environment.     

Mite allergen extracts and clinical practice

Objective

To provide physicians, researchers, and other interested health care professionals with information about how mite source materials and allergen extracts are manufactured, including the critical process parameters that can affect the final composition of allergenic extracts available for clinical use.

Mite antigen and allergen contents of house dust samples

The house dust mite (Dermatophagoides pteronyssinus) antigen and allergen contents were measured by enzyme-linked immunosorbent assay (ELISA) with enzyme-labelled anti-human IgE and anti-mite rabbit IgG antibodies. Antigen content was high in dust samples from homes of patients with allergy but not in samples from homes of patients with Kawasaki disease or of normal control subjects. Allergen content was high in dust samples from homes of Kawasaki disease patients. However, the values overlapped, and we considered these differences to be of little ecological significance, although the assay method itself is useful.     

Current mite,cat, and dog allergen exposure,pet ownership,and sensitization to inhalant allergens in adults

BACKGROUND: Simultaneous exposure to more than one allergen might modify the effect of individual allergens. OBJECTIVE: The purpose of this study was to investigate the effect of current exposures to mite, cat, and dog allergen and pet ownership on sensitization in adults. METHODS: Questionnaires, skin tests, and home visits (Der p 1, Fel d 1, and Can f 1, ELISA; mattresses, living room floors) were performed in 2502 adults. Allergen exposure was treated as a continuous variable and divided into quartiles. To investigate the interaction between allergens, quartiles for 3 allergens were added, creating arbitrary combined exposure categories. RESULTS: In the univariate analysis, mite sensitization was associated with Der p 1 in mattresses (odds ratio [OR], 1.10; 95% CI, 1.01 to 1.19; P =.03) and with Can f 1 in living room floors (OR, 1.08; 95% CI, 1.00 to 1.17; P =.05). In a multivariate regression analysis, Der p 1 in mattresses remained an independent associate of mite sensitization (OR, 1.12; 95% CI, 1.02 to 1.23; P =.03) and pollen sensitization (OR, 1.23; 95% CI, 1.11 to 1.36; P =.0001). The proportion of subjects sensitized to mite increased significantly with the increasing combined exposure categories (P <.0001). The highest prevalence of sensitization to cat and dog was in the medium combined exposure categories. Cat ownership was associated with a reduced prevalence of sensitization to cats (P =.002) and a reduced prevalence of sensitization to dog (P =.003) but had no effect on sensitization to mite and pollen. CONCLUSIONS: Sensitization to dust mites increased with the increasing combined exposure. Cat ownership was associated with a lower prevalence of sensitization to cat and dog but not to mite and grass pollen.     

Mite and mite allergen removal during machine washing of laundry

BACKGROUND: Few studies have investigated live house dust mite and mite allergen removal from clothing and bedding by washing machines. No studies have investigated the transfer of mites from infested to uninfested clothing and bedding during washing. OBJECTIVE: The purpose of this study was to wash different types of clothing and bedding in residential washing machines to determine the live Dermatophagoides farinae mite and allergen removal and the mite transfer from mite-infested items to mite-free items. METHODS: Clothing and bedding items were machine washed in 6- and 8-lb loads in warm (36 degrees C-38 degrees C) or cold (22 degrees C-27 degrees C) water with and without recommended concentrations of laundry detergent and sodium hypochlorite bleach. Live mites and allergen present in washed versus unwashed and washed mite-infested versus washed mite-free items were compared. RESULTS: Washing clothing and bedding in water alone, detergent, or detergent plus bleach removed 60% to 83% of the live mites. Washing removed more mites from some items than from others. When mite-infested items were washed with identical sets of mite-free items, many live mites were transferred to the previously mite-free items. Overall, 84% of Der f 1 was removed from items washed in water alone or in detergent and 98% from items washed in detergent plus bleach. CONCLUSIONS: Washing clothing and bedding in cold or warm water with detergent or detergent plus bleach removed most allergen and a significant (P <.05) portion of live mites. Repeated washing is required to further reduce mite levels. Live mites were transferred from mite-infested to mite-free items during washing.     

Mite allergen and allergoid stimulation of histamine secretion by mast cells

Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 116, N ^o 9, pp. 311–313, September, 1993     

Mite allergen content in commercial extracts and in bed dust determined by radioallergosorbent tests

Radioallergosorbent (RAST) direct binding and inhibition type assays were used to quantitate the mite (Dermatophagoides pteronyssinus) allergen content of four commercial mite extracts and a laboratory prepared extract from freeze-dried mites. The content of mite allergen in extracts prepared from twenty samples of dust vacuumed from bedding was measured by RAST inhibition assay. The four commercial mite extracts designated A, B, C and D, and the laboratory extract, designated L, contained 52, 265, 108, 1.5 and 581 arbitrary units of allergen/ml for the direct binding assay and 128, 111, 217, ～1 and 1083 arbitrary, but different, units of allergen/ml for the inhibition assay respectively. Qualitative differences between at least two extracts were suggested by the different slopes obtained when allergen binding of anti IgE was plotted against the volume of extract used in the direct binding assay. Differences in slope between the two extracts were also apparent when they were used in the inhibition assay. The quantities of mite allergen/gm of bed dust expressed in arbitrary units for the inhibition assay were 24 to 457 (mean 129) units. These quantities are similar to and sometimes greater than the quantity in 1 ml of mite extract and so confirm bed dust as a potent source of mite allergen. There was no significant correlation between the weight of dust, the numbers of dead and live mites and the allergen content of dust.     

Mite allergen content in mattress dust of Dermatophagoides-allergic asthmatics/rhinitics and matched controls

It has been suggested that the mites Dermatophagoides pteronyssinus and D.farinae are important indoor environmental factors facilitating both the sensitization of atopic subjects and asthmatic attacks of house dust-sensitive patients. Contradictory results have been reported about the current exposure to mites or their allergens among patients and control groups of atopic or non-atopic subjects. In order to determine whether there is a difference in mite exposure levels between D. pteronyssinus-sensitized asthmatics and/or rhinitis and control subjects we considered a case-control study of 70 patients with asthma and/or rhinitis and positive skin test reactions to D. pteronyssinus and twice as many control subjects who were matched as to age and sex. The first control subject for each patient was an immediate neighbour of the patient and the second was a patient arbitrarily chosen among hospitalized patients. Mite allergen exposure was measured in mattress dust collected under standardized conditions, by measuring Der p I +Derf I content and by performing a semiquantitative guanine determination (Acarex-test^R). The content of Der p I and Der f I was very high both in the homes of patients and those of healthy individuals: 69% of the total samples contained more than 10 μg Der p I + Der f I/g of dust. There was no significant difference between cases and controls with respect to Der p I, Der f I, Der p I + Der f I content and Acarex^R class distributions. The calculated odds-ratios associated with the Acarex test^R and the mite allergens did not differ significantly from the level 1.0. Our findings show that in a Rhine valley city such as Strasbourg with a high mite allergen load there is no difference in mite exposure between D. pteronyssinus-sensitized patients and controls who can be considered not to differ from the general population with respect to atopy.     

Household mouse allergen exposure and asthma morbidity in inner-city preschool children.

BACKGROUND: Inner-city children experience disproportionate asthma morbidity, and suspected reasons include indoor environmental exposures. OBJECTIVE: To determine if mouse allergen exposure is a risk factor for asthma morbidity. METHODS: Preschool children with asthma were recruited from inner-city Baltimore, MD. Skin testing was performed and blood was collected at the baseline visit for quantification of mouse allergen specific IgE. A questionnaire evaluated symptoms, medication, and health care use at baseline, 3 months, and 6 months. A trained technician collected dust samples from the child's home for analysis of Mus m 1 at baseline, 3 months, and 6 months. Outcomes were compared between mouse-sensitized, highly exposed children and all other children. RESULTS: A total of 127 children had complete data for mouse sensitization status and bedroom settled dust mouse allergen levels at baseline. The mean age of the children was 4.4 years, 92% were African American, and 26% were sensitized to mouse. Mouse-sensitized children exposed to higher levels of Mus m 1 (>0.5 microg/g) had 50% more days of symptoms (incidence rate ratio [IRR], 1.5; 95% confidence interval [CI], 1.1-2.1) and 80% more days of beta-agonist use than other children (IRR, 1.8; 95% CI, 1.3-2.5). Children in the sensitized and highly exposed group were also more likely to have an unscheduled physician visit (odds ratio [OR], 3.1; 95% CI, 1.6-6.3), emergency department visit (OR, 2.1; 95% CI, 1.1-4.1), and hospitalization (OR, 36.6; 95% CI, 4.1-327.3) than other children. These associations between mouse allergen exposure and asthma symptoms and morbidity remained statistically significant after adjusting for potential confounders, including atopy and cockroach sensitization and exposure. CONCLUSIONS: In mouse-sensitized inner-city children, exposure to mouse allergen may be an important cause of asthma morbidity.     

House dust mite allergen exposure in infancy

BACKGROUND: Infancy may be a critical time for exposure to house dust mite allergens, when exposure to high levels can increase the risk of allergic sensitization and the development of asthma in later life. OBJECTIVE: To measure house dust mite allergen (Der p 1) concentration in the infants' environment and examine lifestyle factors which may influence mite allergen exposure. METHODS: Infants aged between 4 and 12 months (n = 134) from the western region of Sydney, Australia. participated. Reservoir dust samples were collected from four sites within each home: infant's bed, second bed (adult or second child's bed), lounge floor and sheepskins (where available). Settling aeroallergen was collected for 10-14 d in Petri dishes in the infant's room. Der p 1 was measured by ELISA. A questionnaire on types of bedding, sleeping and playing patterns of the infant was completed by the parents at the time of dust collection. RESULTS: All infants were exposed to at least one site with Der p 1 concentrations greater than 10 microg/g fine dust. The mean settling aeroallergen level in the infants' room was 24 ng De p l/m2 day and this was weakly related to bed allergen levels (r=0.21, P<0.05). Mattress type had a weak effect on Der p 1 levels as measured in the whole bed (P = 0.07), while bed cover and bed type had no effect (P>0.6). The mean product of time spent at a site and its allergen concentration was highest for beds in 69% of infants. CONCLUSION: The high level of allergen exposure in the environment of this group of infants places them at an increased risk of early sensitization and development of asthma. Any strategy to reduce asthma prevalence should address these high and avoidable levels.     

Cockroach allergen exposure and risk of asthma

Cockroach sensitization is an important risk factor for the development of asthma. However, its underlying immune mechanisms and the genetic etiology for differences in allergic responses remain unclear. Cockroach allergens identification and their expression as biologically active recombinant proteins have provided a basis for studying the mechanisms regarding cockroach allergen‐induced allergic sensitization and asthma. Glycans in allergens may play a crucial role in the immunogenicity of allergic diseases. Protease‐activated receptor (PAR)‐2, Toll‐like receptor (TLR), and C‐type lectin receptors have been suggested to be important for the penetration of cockroach allergens through epithelial cells to mediate allergen uptake, dendritic cell maturation, antigen‐presenting cell (APC) function in T‐cell polarization, and cytokine production. Environmental pollutants, which often coexist with the allergen, could synergistically elicit allergic inflammation, and aryl hydrocarbon receptor (AhR) activation and signaling may serve as a link between these two elements. Genetic factors may also play an important role in conferring the susceptibility to cockroach sensitization. Several genes have been associated with cockroach sensitization and asthma‐related phenotypes. In this review, we will discuss the epidemiological evidence for cockroach allergen‐induced asthma, cockroach allergens, the mechanisms regarding cockroach allergen‐induced innate immune responses, and the genetic basis for cockroach sensitization.     

Mite allergen decreases DC-SIGN expression and modulates human dendritic cell differentiation and function in allergic asthma

House dust mites (HDMs) induce allergic asthma in sensitized individuals, although how HDMs activate immature mucosal dendritic cells (DCs) to render the T helper cell type 2 (Th2)-mediated immune response is unclear. In this study, our results showed a significant calcium-dependent lectin binding of Dermatophagoides pteronyssinus (Der p) extracts to DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), the C-type lectin receptors (CLRs) of DCs. Moreover, monocyte-derived DCs (MDDCs) of Der p-sensitized asthmatics (AS) exhibited decreased expression of DC-SIGN, increased endocytosis, and impaired differentiation of DC precursors. The Der p-induced downregulation of DC-SIGN expression in the differentiation of immature MDDCs may be because of the internalization of Der p-DC-SIGN complex. MDDCs of AS produced more interleukin (IL)-6 and less IL-12p70 cytokines when stimulated with lipopolysaccharide (LPS) or Der p than those of nonallergic controls (NC). In the co-culture experiments, MDDCs pretreated with Der p induced GATA-3 expression and IL-4 cytokine productions in naive CD4(+) T cells. These effects of Der p on the differentiation and function of MDDCs could be partially blocked by anti-DC-SIGN antibodies. In conclusion, our results suggest a critical step of allergen sensitization that involves CLRs in the innate immune response of DCs, which may provide a therapeutic or preventive potential for allergic asthma.     

Mouse allergen. II. The relationship of mouse allergen exposure to mouse sensitization and asthma morbidity in inner-city children with asthma

BACKGROUND: Although mouse allergen is known to cause occupational asthma in laboratory workers, its potential significance in home environments has never been studied. OBJECTIVE: This study was designed to define the prevalence of mouse sensitivity and its relationship to mouse allergen exposure and disease activity in inner-city children with asthma. METHODS: A subset of 499 subjects from the National Cooperative Inner-City Asthma Study had dust samples adequate for mouse allergen analysis, as well as valid puncture skin test (PST) results. Data were analyzed to relate mouse allergen exposure and other risk factors to mouse sensitization and asthma morbidity. RESULTS: Eighty-nine (18%) of the 499 children had a positive mouse skin test response. Children whose homes had mouse allergen levels above the median (1.60 microg/g) in the kitchen had a significantly higher rate of mouse sensitization (23% vs 11%, P =. 007). Atopy was also significantly related to mouse sensitization, with 40% of those with more than 4 positive PST responses having mouse sensitivity compared with 4% of those with no other positive PST responses (P <.0001). When atopy and exposure were considered together, 53% of those with more than 4 positive PST responses and allergen levels above the median had a positive PST response to mouse allergen compared with 22% of those with more than 4 positive PST responses and allergen levels below the median (P <.0001). The relationship among mouse allergen exposure, sensitization, and any measures of asthma morbidity was not statistically significant. CONCLUSIONS: Mouse allergen may be an important indoor allergen in inner-city children with asthma, with exposure and atopy contributing to mouse sensitization.     

Mattress encasings and mite allergen levels in the Prevention and Incidence of Asthma and Mite Allergy study

BACKGROUND: Reduction of allergen exposure from birth may reduce sensitization and subsequent allergic disease. OBJECTIVE: To measure the influence of mite allergen-impermeable mattress encasings and cotton placebo encasings on the amount of dust and mite allergen in beds. METHODS: A total of 810 children with allergic mothers took part in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study. Allergen-impermeable and placebo mattress encasings were applied to the childrens' and the parents' beds before birth. Dust samples were taken from the beds of children and their parents before birth and 3 and 12 months after birth. Extracts of dust samples were analysed for mite allergens (Der p 1 and Der f 1). RESULTS: Active mattress encasings were significantly more effective in reducing dust and mite allergen levels than placebo encasings. Mite allergen levels were low in general and the treatment effect was modest. Twelve months after birth, mattresses with active mattress encasings had about half the amount of Der 1 (Der p 1 + Der f 1)/m2, compared to mattresses with placebo encasings, for the child's and the parental mattress. CONCLUSION: This study shows that mite-impermeable mattress encasings have a significant but modest effect on dust and mite allergen levels of mattresses with low initial mite allergen levels, compared to placebo.     

Rapid appearance of plasmin in tear fluid after ocular allergen exposure.

Specific allergens were applied topically to the conjunctivae of 18 allergic patients. In cases with positive allergic reaction, proteolytic activity, identified as plasmin using zymographic analysis and a monoclonal anticatalytic antibody to plasmin, was found to appear within 3-5 min in the tear fluid, reaching concentrations of 2.2-28.6 micrograms/ml. No plasmin was detected, either in the tear fluid of 30 unchallenged non-atopic control persons, or atopic patients provoked with a test material that had given no reaction in a skin prick test. These findings suggest that generation of plasmin is a consequence of the conjunctival allergic reaction.