B. Fahlbusch

Pets and vermin are associated with high endotoxin levels in house dust.

Background Previous studies have shown that the risk for allergic sensitization is lower in children who grew up on farms and in young adults who were exposed to dogs in early childhood. A higher microbial exposure in general and in particular to endotoxin in early childhood might contribute to this lower risk of atopy.

Reproducibility of allergen, endotoxin and fungi measurements in the indoor environment

Measurements of biocontaminants in settled house dust once a year are commonly used to assess long-term exposure. To examine stability over time and seasonal variation, we measured concentrations of mite and cat allergens, endotoxin and mold spores in living room floor dust in 745 German homes collected twice a year in two different seasons. The study population consisted of adults and children living in five different areas in Germany. All dust samples were collected in a standardized manner from the living room floor and taken during the years 1995 to 1998. The median interval between the two dust samplings was approximately 7 months. Mite and cat allergens were measured in settled house dust by monoclonal antibodies, endotoxin by the limulus amebocyte lysate method, and total spore counts by cultural methods. Crude Pearsons correlation coefficients between log-transformed concentrations in the first and second dust samples ranged between 0.65 and 0.75 for allergens, 0.59 for endotoxin and only 0.06 for total spore counts. The strongest and most consistent seasonal effects were observed for fungi with highest levels in July–September. Cat allergen concentrations were found consistently to be increased in January–March. Mite allergens did not show a strong and consistent seasonal pattern. We conclude that repeated measurements of mite and cat allergens and endotoxin in settled house dust improve the estimate for annual mean concentrations. However, even a single observation of these biocontaminants may be a good proxy for a 1-year exposure since repeated measures were highly correlated. However, repeated measurements of fungi levels were only weakly correlated and thus repeated observations for assessment of annual means of total spore counts are needed.

Beta(1-->3)-glucan in house dust of German homes: housing characteristics, occupant behavior, and relations with endotoxins, allergens, and molds.

beta(1-->3)-Glucans are potent proinflammatory agents that have been suggested to play a role in indoor-related respiratory health effects. The aim of this study was to assess whether beta(1-->3)-glucan concentrations in house dust are correlated with levels of endotoxins, allergens, and culturable mold spore counts in house dust. Further, the associations of beta(1-->3)-glucan with housing characteristics and occupant behavior were assessed. beta(1-->3)-Glucan was measured in settled house dust from living room floors of 395 homes of two German cities, Erfurt and Hamburg, with a specific enzyme immunoassay. Concentrations ranged from below the limit of detection to 19,013 microg/m(2) (22,588 microg/g dust). Concentrations per square meter were found to be correlated with endotoxins, mite and cat allergens, and culturable mold spores. Correlations were weaker when concentrations were expressed per gram of dust, indicating that variance in concentrations of all factors is largely determined by the amount of dust sampled. Associations between beta(1-->3)-glucan, housing characteristics, and occupant behavior were found for concentrations per square meter but not for concentrations per gram of dust. The following characteristics were associated with a significant increase in beta(1-->3)-glucan levels: carpets in the living room [means ratio (MR) = 1.9-2.1], keeping a dog inside (MR = 1.4), use of the home by four or more persons (MR = 1.4), use of the living room for > 180 hr/week (MR = 2.1), lower frequency of vacuum cleaning (MR = 1.6-3.0) and dust cleaning (MR = 1.2 and 1.4, respectively), and presence of mold spots during the past 12 months (MR = 1.4). We conclude that that the amount of dust sampled can be used as a proxy for hygiene and that beta(1-->3)-glucan concentrations per square meter are related to the amount of dust sampled.

Investigation of the stability of apple allergen extracts

To determine optimal conditions for allergen preservation, we investigated the influence of different stabilizing additives and of storage temperature on the allergen activity of apple protein preparations, obtained by extraction in phosphate buffer or by precipitation in diacetone alcohol and resolubilization in phosphate buffer in the presence or absence of enzyme inhibitors. For this purpose, the extracts were stored for 6 months either in frozen state at −20° C or in lyophilized state at −20° C, 4° C, or room temperature and were characterized by SDS‐PAGE, immunoblot, ELISA inhibition, and prick test. The highest stability revealed the extracts that were prepared by precipitation in the organic solvent in the presence of enzyme inhibitors, lyophilized, and stored at −20° C. For storage of extract solutions at 4° C, PBS/glycerol and cysteine/sodium citrate/glycerol were found to be the most effective stabilizing additives.

Indoor determinants of Der p 1 and Der f 1 concentrations in house dust are different

Exposure to mite allergens is a major risk factor for sensitization and the development of asthma. Der p 1 and Der f 1 content in homes and probably the proportion of both antigens is highly variable even in the same geographical area.

Exposure to house dust endotoxin and allergic sensitization in adults

Background:  It has been suggested that exposure to elevated levels of endotoxin decreases the risk of allergic sensitization.

Repeated measurements of allergens and endotoxin in settled house dust over a time period of 6 years

Background  Studies investigating the effect of exposure to indoor allergens and endotoxin on human respiratory health usually take dust samples only at one single point of time and consider them to be representative for the indoor biocontaminant burden during a time period of several years. This singly measured biocontaminant concentration is related to adverse respiratory outcomes such as asthma, wheeze or others.

Optimization of apple allergen preparation for in vivo and in vitro diagnostics

The aim of our investigation was to obtain a well‐characterized active apple extract suitable for both in vivo and in vitro diagnostics by a technically simple method. For this purpose, apple extracts were prepared by homogenization in potassium phosphate buffer or by precipitation in organic solvents and resolubilization in potassium phosphate buffer in the presence or in the absence of enzyme inhibitors. These extracts were comparatively investigated by means of SDS‐PAGE, two‐dimensional electrophoresis, immunoblotting, RAST inhibition, and prick test. The in vitro investigations indicated that extracts prepared by precipitation in organic solvents (diacetone alcohol) at ‐20°C have a higher allergen activity than those prepared by extraction in aqueous solutions. From the in vivo tests (prick test), it was concluded that application of inhibitors of cytoplasmic enzymes (phenol oxidases, peroxidases, proteases) already during extraction is an essential precondition for active prick test solutions. Correspondingly, the extract obtained by solvent precipitation in the presence of enzyme inhibitors appeared to be most suitable for clinical application.

Purification and partial characterization of the major allergen, Cav p 1, from guinea pig Cavia porcellus

Background: Allergic reaction to guinea pig has been recognized as a problem in domestic settings and work environments for many years. Until recently, limited information was available on the properties of guinea pig allergen(s). In this study the major allergen Cav p 1 was characterized and the N‐terminal amino‐acid sequence was determined.

The effect of storage on allergen and microbial agent levels in frozen house dust.

Background: House dust samples collected for exposure studies are often stored for variable time periods until analysis. However, there is currently no information on the effects of dust storage on the content of biocontaminants. Therefore, associations were analysed between the levels of mite allergens (Der p 1, Der f 1), cat allergen (Fel d 1) and microbial components (endotoxin, β(1→3)‐glucan) on the one hand and the storage duration of dust samples at −20°C on the other hand.